ACT Math Practice Questions with Detailed Solutions - Sample 1

Detailed solutions and explanations to 60 math questions are presented. The questions are from ACT sample 1.

  1. Question

    \(4 \times 10^{-5} =\)

    Solution

    Rewrite \(4 \times 10^{-5}\) as

    \[ \frac{4}{10^{5}} = \frac{4}{100,\!000} = 0.00004 \]
  2. Question

    Which of the following is equivalent to \((x)(x)(x)(x^{3})\), for all \(x\)?

    Solution

    Rewrite \((x)(x)(x)(x^{3})\) as

    \[ (x)(x)(x)(x^{3}) = (x)^{3} (x^{3}) = x^{6} \]
  3. Question

    There are 15 balls in a box: 8 balls are green, 4 are blue and 3 are white. Then 1 green and 1 blue balls are taken from the box and put away. What is the probability that a blue ball is selected at random from the box?

    Solution

    If 1 green and 1 blue ball are taken from the box, then there are 7 green, 3 blue and 3 white balls, a total of 13 balls. If one ball is selected at random, the probability that it is blue is given by

    \[ \frac{3}{13} \]
  4. Question

    The length of a rectangle is 3 times its width. If the width of the rectangle is 5 inches, what is the rectangle's area, in square inches?

    Solution

    If the width is 5 in and the length is 3 times the width, then the length is

    \[ 3 \times 5 = 15 \text{ in} \]

    The area is given by

    \[ 5 \times 15 = 75 \text{ in}^2 \]
  5. Question

    For all \(x > 2\), \(\frac{2x^{2} + 2x - 12}{x - 2}\) simplifies to

    Solution

    We first factor \(2x^{2} + 2x - 12\) as follows

    \[ 2x^{2} + 2x - 12 = 2(x^{2} + x - 6) = 2(x + 3)(x - 2) \]

    We simplify as follows

    \[ \frac{2x^{2} + 2x - 12}{x - 2} = \frac{2(x + 3)(x - 2)}{x - 2} = 2(x + 3) \]
  6. Question

    If the hypotenuse of a right triangle is 10 inches long and one of its legs is 5 inches long, how long is the other leg?

    Solution

    Let \(x\) be the length of second leg and apply Pythagoras' theorem as follows

    \[ 10^{2} = 5^{2} + x^{2} \]

    Solve for \(x\)

    \[ x = \sqrt{100 - 25} = \sqrt{75} = 5\sqrt{3} \]
  7. Question

    In the standard \((x,y)\) coordinate plane, the graph of \((x + 3)^{2} + (y + 5)^{2} = 16\) is a circle. What is the circumference of the circle, expressed in coordinate units?

    Solution

    Rewrite the given equation as follows

    \[ (x + 3)^{2} + (y + 5)^{2} = 4^{2} \]

    The radius of the circle is 4 and therefore the circumference is given by

    \[ 2 \times 4 \times \pi = 8\pi \]
  8. Question

    How many solutions are there to the equation \(x^{2} - 7 = 0\)?

    Solution

    Rewrite the given equation as follows

    \[ x^{2} = 7 \]

    The above equation has two solutions \(+\sqrt{7}\) and \(-\sqrt{7}\).

  9. Question

    A circle with center \((4,-5)\) is tangent to the y-axis in the standard \((x,y)\) coordinate plane. What is the radius of this circle?

    Solution

    The radius is given by the distance between the center of the circle \((4, -5)\) and the y-axis which is 4.

  10. Question

    Angle \(A\) is an acute angle and \(\sin(A) = \frac{11}{14}\). What is the value of \(\cos(A)\)?

    Solution

    \(\sin(A)\) and \(\cos(A)\) are related by

    \[ \sin^{2}(A) + \cos^{2}(A) = 1 \]

    Substitute \(\sin(A)\) by \(\frac{11}{14}\) in the above equation

    \[ \left(\frac{11}{14}\right)^{2} + \cos^{2}(A) = 1 \]

    Solve for \(\cos(A)\) and select the positive value since \(A\) is an acute angle

    \[ \cos(A) = \sqrt{1 - \frac{121}{196}} = \sqrt{\frac{196 - 121}{196}} = \frac{\sqrt{75}}{14} = \frac{5\sqrt{3}}{14} \]
  11. Question

    What are the values of \(a\) and \(b\), if any, where \(-a|b + 4| > 0\)?

    Solution

    For \(-a |b + 4| > 0\), \(-a\) must be positive and \(|b + 4|\) must also be positive. Which means \(a\) must be negative and \(b + 4 \neq 0\) or \(b \neq -4\).

    \(a < 0\) and \(b \neq -4\).

  12. Question

    In a shipment of televisions, \(1/50\) of the televisions are defective. What is the ratio of defective to nondefective televisions?

    Solution

    If \(1/50\) are defective, then

    \[ 1 - \frac{1}{50} = \frac{49}{50} \text{ are not defective} \]

    So if \(x\) is the total number of TV sets, then \(\frac{1}{50}x\) are defective and \(\frac{49}{50}x\) are not defective. Hence the ratio of defective to nondefective is given by

    \[ \frac{x(1/50)}{x(49/50)} = \frac{1}{50} \cdot \frac{50}{49} = \frac{1}{49} \]
  13. Question

    Which of the following is divisible (with no remainder) by 4?

    Solution

    A whole number is divisible by 4 if the number formed by the last two digits is divisible by 4. The numbers formed by the last two digits of the given numbers are: 33, 56, 69, 17 and 95. The only one that is divisible by 4 is 56 and therefore 510056 is the only number in the list that is divisible by 4.

  14. Question

    A particle travels \(1 \times 10^{6}\) meters per second in a straight line for \(5 \times 10^{-6}\) seconds. How many meters has it traveled?

    Solution

    We are given the speed \(1 \times 10^{6}\) m/s and the time \(5 \times 10^{-6}\) seconds. The distance \(d\) is given by

    \[ d = (1 \times 10^{6} \text{ m/s}) \times (5 \times 10^{-6} \text{ s}) = 5 \times 10^{6 + (-6)} = 5 \times 10^{0} = 5 \text{ meters} \]
  15. Question

    The lengths of sides AB and AC in the triangle below are equal. What is the measure of angle \(A\)?

    act problem 15

    Solution

    Since the lengths of sides AB and AC are equal, then the triangle is isosceles and therefore angles B and C are equal in size. Hence angle \(A\) is given by

    \[ 180^{\circ} - (70^{\circ} + 70^{\circ}) = 40^{\circ} \]
  16. Question

    In the figure below ABC is an equilateral triangle. AH is perpendicular to BC and has a length of \(2\sqrt{3}\) inches. What is the area, in square inches, of triangle \(ABC\)?

    act problem 16

    Solution

    Let \(x\) be the length of the side of the equilateral triangle. Since \(AH\) is perpendicular to \(BC\), then by Pythagoras' theorem (applied to triangle ABH) we can write

    \[ x^{2} = \left(\frac{x}{2}\right)^{2} + (2\sqrt{3})^{2} \]

    Simplify the above equation

    \[ x^{2} = \frac{x^{2}}{4} + 12 \] \[ 4x^{2} = x^{2} + 48 \] \[ 3x^{2} = 48 \] \[ x^{2} = 16 \]

    Solve to find \(x = 4\)

    The area \(A\) of the triangle is given by

    \[ A = \frac{1}{2} \times AH \times BC = \frac{1}{2} \times 2\sqrt{3} \times 4 = 4\sqrt{3} \]
  17. Question

    If \(8y = 3x - 11\), then \(x =\)

    Solution

    We are asked to solve for \(x\). Add 11 to both sides of the equation and simplify

    \[ 8y + 11 = 3x - 11 + 11 \] \[ 8y + 11 = 3x \]

    Divide both sides of the equation by 3

    \[ x = \frac{8y + 11}{3} \]
  18. Question

    Which of the statements describes the solution set for \(-2(x + 8) = -2x + 20\)?

    A) \(x = -2\) only

    B) \(x = 0\) only

    C) \(x = 20\) only

    D) There are no solutions for this equation.

    E) All real numbers are solutions of this equation.

    Solution

    Expand the left side of the equation

    \[ -2x - 16 = -2x + 20 \]

    Add \(2x\) to both sides

    \[ -2x - 16 + 2x = -2x + 20 + 2x \] \[ -16 = 20 \]

    The last statement is always false, hence the given equation has no solution.

  19. Question

    When graphed in the \((x,y)\) coordinate plane, at what point do the lines \(2x + 3y = 5\) and \(x = -2\) intersect?

    Solution

    We need to solve the system of equations:

    \[ \begin{cases} 2x + 3y = 5 \\ x = -2 \end{cases} \]

    Substitute \(x = -2\) into the first equation:

    \[ 2(-2) + 3y = 5 \] \[ -4 + 3y = 5 \] \[ 3y = 9 \] \[ y = 3 \]

    The lines intersect at \((-2, 3)\).

  20. Question

    The area of a trapezoid is \(0.5h(b_1 + b_2)\), where \(h\) is the altitude, and \(b_1\) and \(b_2\) are the lengths of the parallel bases. If a trapezoid has an altitude of 15 inches, an area of 105 square inches, and one of the bases 22 inches, what is the perimeter, in inches, of the trapezoid?

    Solution

    Given the area, \(h\) and \(b_1\), we find \(b_2\):

    \[ 105 = 0.5 \times 15 \times (22 + b_2) \] \[ 105 = 7.5 \times (22 + b_2) \] \[ b_2 = \frac{105}{7.5} - 22 = 14 - 22 = -8 \]

    The base of a trapezoid cannot be negative. Therefore, no trapezoid exists with the given dimensions.

  21. Question

    If you drove at an average speed of 66 miles per hour, what distance, in miles, did you drive in 99 minutes?

    Solution

    First convert the speed to miles per minute:

    \[ \frac{66}{60} = 1.1 \text{ miles per minute} \]

    The distance is:

    \[ 1.1 \times 99 = 108.9 \text{ miles} \]
  22. Question

    If \(x\) and \(y\) are any real numbers such that \(0 < x < 2 < y\), which of these must be true?

    A) \(x < \frac{xy}{2} < y\)

    B) \(0 < xy < 2x\)

    C) \(x < xy < 2\)

    D) \(0 < xy < 2\)

    E) \(xy < y\)

    Solution

    Since both \(x\) and \(y\) are positive, the inequality \(x < 2 < y\) implies

    \[ \frac{1}{x} > \frac{1}{2} > \frac{1}{y} \]

    Multiply all terms by \(xy\) (positive) and simplify:

    \[ y > \frac{xy}{2} > x \]

    Which is equivalent to

    \[ x < \frac{xy}{2} < y \]

    This corresponds to option A. Using \(x=1.8\) and \(y=2.1\), it can be shown that B, C, D, and E are not necessarily true.

  23. Question

    In the right triangle ABC below, what is the cosine of angle \(A\)?

    act problem 23

    Solution

    First find the hypotenuse \(BA\):

    \[ BA = \sqrt{3^{2} + 4^{2}} = 5 \]

    Then

    \[ \cos(A) = \frac{\text{adjacent}}{\text{hypotenuse}} = \frac{3}{5} \]
  24. Question

    The graph of \(y = \frac{2}{x - 3}\) is shown below. Among the following, which is the best possible graphical representation of \(y = -\frac{2}{|x - 3|}\)?

    act problem 24

    act solution 24

    Solution

    \(|x - 3|\) is always positive or zero. Hence \(-\frac{2}{|x - 3|}\) is always negative except at \(x = 3\) where it is undefined. The graph in C is entirely below the x-axis and is therefore the closest to the graph of \(y = -\frac{2}{|x - 3|}\).

  25. Question

    What is the slope of the line \(4x = -3y + 8\)?

    Solution

    Write the equation in slope-intercept form \(y = mx + b\):

    \[ 4x = -3y + 8 \] \[ 3y = -4x + 8 \] \[ y = -\frac{4}{3}x + \frac{8}{3} \]

    The slope is \(-\frac{4}{3}\).

  26. Question

    In the figure below, B is on \(\overline{AD}\), \(\angle BAC\) and \(\angle ACB\) measure \(26^{\circ}\) and \(131^{\circ}\) respectively. What is the measure of \(\angle CBD\)?

    act problem 26

    Solution

    First find \(\angle ABC\) using the sum of angles in triangle ABC:

    \[ \angle ABC = 180^{\circ} - (26^{\circ} + 131^{\circ}) = 23^{\circ} \]

    Angles ABC and CBD are supplementary:

    \[ \angle CBD = 180^{\circ} - 23^{\circ} = 157^{\circ} \]
  27. Question

    Which of the following is equal to \(\sqrt{45}\)?

    Solution

    \[ \sqrt{45} = \sqrt{9 \times 5} = \sqrt{9} \cdot \sqrt{5} = 3\sqrt{5} \]
  28. Question

    What is the smallest value of \(x\) that satisfies the equation \(x(x + 4) = -3\)?

    Solution

    Rewrite the equation:

    \[ x^{2} + 4x + 3 = 0 \]

    Factor:

    \[ (x + 3)(x + 1) = 0 \]

    Solutions: \(x = -3\) and \(x = -1\). The smallest is \(-3\).

  29. Question

    A group of 7 friends are having lunch together. Each person eats at least \(\frac{3}{4}\) of a pizza. What is the smallest number of whole pizzas needed for lunch?

    Solution

    The total amount of pizza needed is at least:

    \[ 7 \times \frac{3}{4} = \frac{21}{4} = 5.25 \]

    Therefore, at least 6 whole pizzas are needed.

  30. Question

    All axes in the graphs below have the same scales. Which one of the graphs is closest to the graph of \(y = -2x + 2\)?

    act problem 30

    Solution

    Find the intercepts:

    x-intercept: set \(y=0\):

    \[ 0 = -2x + 2 \Rightarrow x = 1 \quad (1,0) \]

    y-intercept: set \(x=0\):

    \[ y = 2 \quad (0,2) \]

    Using these intercepts, the closest graph is D.

  31. Question

    The measures of angles A, B and C of a triangle are in the ratio 3:4:5. What is the measure, in degrees, of the largest angle?

    Solution

    Let the angles be \(3x\), \(4x\), and \(5x\). Their sum is \(180^{\circ}\):

    \[ 3x + 4x + 5x = 180^{\circ} \] \[ 12x = 180^{\circ} \] \[ x = 15^{\circ} \]

    The largest angle is \(5x = 5 \times 15^{\circ} = 75^{\circ}\).

  32. Question

    There are \(n\) students in a school. If \(r\%\) among the students are 12 years or younger, which of the following expressions represents the number of students who are older than 12?

    Solution

    If \(r\%\) are 12 or younger, then \((100 - r)\%\) are older than 12. The number of students older than 12 is:

    \[ n \times \frac{100 - r}{100} \]
  33. Question

    If \(x + 4y = 5\) and \(5x + 6y = 7\), then \(3x + 5y = ?\)

    Solution

    Add the two equations:

    \[ (x + 4y) + (5x + 6y) = 5 + 7 \] \[ 6x + 10y = 12 \]

    Divide by 2:

    \[ 3x + 5y = 6 \]
  34. Question

    Which integer is nearest to \(\frac{\sqrt{2100}}{\sqrt{7}}\)?

    Solution

    \[ \frac{\sqrt{2100}}{\sqrt{7}} = \sqrt{\frac{2100}{7}} = \sqrt{300} \approx 17.32 \]

    The nearest integer is 17.

  35. Question

    For all real numbers \(x\), the minimum value of \(1 + 2\cos(4x)\) is

    Solution

    The range of \(\cos(4x)\) is \([-1, 1]\). Therefore,

    \[ -2 \leq 2\cos(4x) \leq 2 \]

    Add 1:

    \[ -1 \leq 1 + 2\cos(4x) \leq 3 \]

    The minimum value is \(-1\).

  36. Question

    What is the largest possible product for 2 odd integers whose sum is equal to 32?

    Solution

    Let the odd integers be \(2n+1\) and \(2k+1\). Their sum is 32:

    \[ (2n+1) + (2k+1) = 32 \] \[ 2n + 2k = 30 \] \[ n + k = 15 \]

    The product \(P\) is:

    \[ P = (2n+1)(2k+1) = 4nk + 2n + 2k + 1 = 4nk + 2(n+k) + 1 = 4nk + 31 \]

    To maximize \(P\), maximize \(nk\) given \(n+k=15\). The maximum occurs when \(n\) and \(k\) are as close as possible. Since \(n\) and \(k\) are integers, the maximum product is when the numbers are 15 and 17 or 17 and 15. The product is \(15 \times 17 = 255\).

  37. Question

    If \((a + b)^{2} = 25\) and \((a - b)^{2} = 45\), then \(a^{2} + b^{2} = ?\)

    Solution

    Expand both equations:

    \[ a^{2} + 2ab + b^{2} = 25 \] \[ a^{2} - 2ab + b^{2} = 45 \]

    Add them:

    \[ 2a^{2} + 2b^{2} = 70 \] \[ a^{2} + b^{2} = 35 \]
  38. Question

    If \(a = 3\), then \(\frac{2}{\frac{1}{7} + \frac{1}{a}} = ?\)

    Solution

    \[ \frac{2}{\frac{1}{7} + \frac{1}{3}} = \frac{2}{\frac{3+7}{21}} = \frac{2}{\frac{10}{21}} = 2 \times \frac{21}{10} = \frac{42}{10} = \frac{21}{5} \]
  39. Question

    A company makes a profit equal to 25% of its sales. The profit is shared equally among the 4 owners of the company. If the company generates sales of $5,000,000, how much money does each one of the owners get?

    Solution

    Profit = \(25\% \times 5,000,000 = 1,250,000\).

    Each owner gets \(\frac{1,250,000}{4} = 312,500\).

  40. Question

    If the expression \(x^{3} + 2hx - 2\) is equal to 6 when \(x = -2\), what is the value of \(h\)?

    Solution

    Substitute \(x = -2\):

    \[ (-2)^{3} + 2h(-2) - 2 = 6 \] \[ -8 - 4h - 2 = 6 \] \[ -4h = 16 \] \[ h = -4 \]
  41. Question

    If \(-\frac{3}{a - 3} = \frac{3}{a + 2}\), then \(a = ?\)

    Solution

    Cross multiply:

    \[ -3(a + 2) = 3(a - 3) \] \[ -3a - 6 = 3a - 9 \] \[ -6a = -3 \] \[ a = \frac{1}{2} \]
  42. Question

    For what negative value of \(k\), the system of equations below has no solutions?

    \[ \begin{cases} 2x + ky = 5 \\ kx + (k+4)y = 7 \end{cases} \]

    Solution

    The system has no solution if the determinant of the coefficient matrix is zero and the equations are inconsistent. The determinant is:

    \[ \begin{vmatrix} 2 & k \\ k & k+4 \end{vmatrix} = 2(k+4) - k^{2} = -k^{2} + 2k + 8 \]

    Set to zero:

    \[ -k^{2} + 2k + 8 = 0 \] \[ k^{2} - 2k - 8 = 0 \] \[ (k-4)(k+2) = 0 \]

    The negative value is \(k = -2\).

  43. Question

    The two legs of a right triangle measure 6 and 8 inches respectively. What is the area of the circle that contains all 3 vertices of the triangle?

    Solution

    The hypotenuse is the diameter of the circle. Find hypotenuse:

    \[ d = \sqrt{6^{2} + 8^{2}} = 10 \]

    Radius \(r = 5\). Area of circle:

    \[ \pi r^{2} = 25\pi \]
  44. Question

    \(X\) and \(Y\) are acute angles such that \(\tan Y = \cot X\). What is the sum, in degrees, of the measures of the angles \(X\) and \(Y\)?

    Solution

    \(\tan Y = \cot X\) implies \(\tan Y = \frac{1}{\tan X}\), so \(\tan X \tan Y = 1\).

    Using the identity:

    \[ \tan(X+Y) = \frac{\tan X + \tan Y}{1 - \tan X \tan Y} \]

    Since \(\tan X \tan Y = 1\), the denominator is zero, so \(\tan(X+Y)\) is undefined, meaning \(X+Y = 90^{\circ}\).

  45. Question

    The measures of the sides of the right triangle below are in inches. What is the value of \(x\)?

    act problem 45

    Solution

    Using tangent:

    \[ \tan(60^{\circ}) = \frac{1}{x} \] \[ x = \frac{1}{\tan(60^{\circ})} = \frac{1}{\sqrt{3}} \]
  46. Question

    Which of the graphs below is the solution set of \(-3x \le 12\)?

    act problem 46

    Solution

    Divide both sides by \(-3\) (reverse inequality):

    \[ x \ge -4 \]

    This corresponds to graph C.

  47. Question

    Which of the lines below is not parallel to the line \(6x - 2y = 10\)?

    A) \(3x - y = 7\)

    B) \(-6x + 2y = 20\)

    C) \(3x + y = 7\)

    D) \(6x - 2y = 5\)

    E) \(x - \frac{y}{3} = 9\)

    Solution

    The slope of the given line is found by rewriting:

    \[ 6x - 2y = 10 \Rightarrow y = 3x - 5 \Rightarrow \text{slope} = 3 \]

    Check each option:

    A) \(y = 3x - 7\), slope 3.

    B) \(y = 3x + 10\), slope 3.

    C) \(y = -3x + 7\), slope -3 → not parallel.

    D) \(y = 3x - \frac{5}{2}\), slope 3.

    E) \(y = 3x - 27\), slope 3.

    Answer is C.

  48. Question

    For what value of \(k\) the equation below has no solution?

    \[ 2x + 3 = x - 2kx - 5 \]

    Solution

    Simplify:

    \[ 2x + 3 = x(1 - 2k) - 5 \] \[ 2x - x(1 - 2k) = -5 - 3 \] \[ x(2 - (1 - 2k)) = -8 \] \[ x(1 + 2k) = -8 \]

    If \(1 + 2k = 0\), then \(k = -\frac{1}{2}\), and the equation becomes \(0 = -8\), which has no solution.

  49. Question

    \(|5 - 2| - |6 - 9| = ?\)

    Solution

    \[ |3| - |-3| = 3 - 3 = 0 \]
  50. Question

    What is the average of \(\frac{7}{8}\) and \(\frac{3}{4}\)?

    Solution

    \[ \frac{\frac{7}{8} + \frac{3}{4}}{2} = \frac{\frac{7}{8} + \frac{6}{8}}{2} = \frac{\frac{13}{8}}{2} = \frac{13}{16} \]
  51. Question

    A solution is made of water and pure acid. If 75% of the solution is water, how many liters of pure acid are in 20 liters of this solution?

    Solution

    If 75% is water, then 25% is acid. The amount of acid is:

    \[ 25\% \times 20 = 0.25 \times 20 = 5 \text{ liters} \]
  52. Question

    The total surface area of all six faces of the rectangular box below is equal to 128 square inches. What is \(x\) in inches?

    act problem 52

    Solution

    The surface area is:

    \[ 2(4x) + 2(4x) + 2(4 \times 4) = 128 \] \[ 8x + 8x + 32 = 128 \] \[ 16x = 96 \] \[ x = 6 \]
  53. Question

    The diagonal of a square has a measure of 12 inches. What is the perimeter, in inches, of this square?

    Solution

    Let side be \(s\). By Pythagoras:

    \[ s^{2} + s^{2} = 12^{2} \] \[ 2s^{2} = 144 \] \[ s^{2} = 72 \] \[ s = 6\sqrt{2} \]

    Perimeter = \(4s = 24\sqrt{2}\).

  54. Question

    The lengths in the rectangle below are in inches. What is the shaded area in square inches?

    act problem 54

    Solution

    Total area of rectangle = \(7 \times (6+4) = 70\).

    Non-shaded area = sum of areas of three triangles:

    \[ \frac{1}{2} \times 6 \times 7 + \frac{1}{2} \times 4 \times 4 + \frac{1}{2} \times 3 \times 2 = 21 + 8 + 3 = 32 \]

    Shaded area = \(70 - 32 = 38\).

  55. Question

    In the right triangle ABC, C is a right angle and the measure of angle B is \(60^{\circ}\). If \(\overline{BC}\) is 20 inches long, then how long is \(\overline{AC}\)?

    act problem 55

    Solution

    Using tangent:

    \[ \tan(60^{\circ}) = \frac{AC}{BC} \] \[ AC = BC \times \tan(60^{\circ}) = 20 \times \sqrt{3} \]
  56. Question

    In the figure below ABC is a right triangle. ABDE is a square of area 200 square inches and BCGF is a square of 100 square inches. What is the length, in inches, of \(\overline{AC}\)?

    act problem 56

    Solution

    Side of square ABDE = \(\sqrt{200} = 10\sqrt{2}\).

    Side of square BCGF = \(\sqrt{100} = 10\).

    Using Pythagoras in triangle ABC:

    \[ AC^{2} = (10\sqrt{2})^{2} + 10^{2} = 200 + 100 = 300 \] \[ AC = \sqrt{300} = 10\sqrt{3} \]
  57. Question

    If \(x = 2.0001\), which of the following expressions has the largest value?

    A) \(\frac{2}{x+2}\)

    B) \(\frac{2}{x-2}\)

    C) \(\frac{x+2}{2}\)

    D) \(\frac{2}{x}\)

    E) \(\frac{x}{2}\)

    Solution

    For \(x=2.0001\), the denominator in B is very small (\(0.0001\)), making the fraction very large. So B has the largest value.

  58. Question

    In the rectangle below, the measure of the length \(\overline{AD}\) is 3 times the measure of the width \(\overline{AB}\). What is the slope of the line segment \(\overline{BD}\)?

    act problem 58

    Solution

    Let \(AB = w\), then \(AD = 3w\). Coordinates: \(B(0,w)\), \(D(3w, 0)\). Slope of BD:

    \[ \frac{0 - w}{3w - 0} = - \frac{1}{3} \]
  59. Question

    What is the product of the two real solutions of the equation \(2x = 3 - x^{2}\)?

    Solution

    Rewrite:

    \[ x^{2} + 2x - 3 = 0 \]

    Factor:

    \[ (x+3)(x-1) = 0 \]

    Solutions: \(x=-3\) and \(x=1\). Product = \(-3 \times 1 = -3\).

  60. Question

    Which of the following equations corresponds the data in the table?

    xy
    -20-1/8
    -10-1/3
    01/2
    52/9
    201/12

    A) \(y = \frac{1}{x+2}\)

    B) \(y = \frac{2}{x+4}\)

    C) \(y = \frac{x-1}{x+2}\)

    D) \(y = \frac{2}{x-2}\)

    E) \(y = \frac{1}{2x+2}\)

    Solution

    Test each option with a point from the table, e.g., (0,1/2):

    A: \(y = \frac{1}{0+2} = \frac{1}{2}\) → works.

    B: \(y = \frac{2}{0+4} = \frac{1}{2}\) → works.

    C: \(y = \frac{0-1}{0+2} = -\frac{1}{2}\) → fails.

    D: \(y = \frac{2}{0-2} = -1\) → fails.

    E: \(y = \frac{1}{0+2} = \frac{1}{2}\) → works.

    Now test another point, e.g., (5,2/9):

    A: \(y = \frac{1}{5+2} = \frac{1}{7}\) → fails.

    B: \(y = \frac{2}{5+4} = \frac{2}{9}\) → works.

    E: \(y = \frac{1}{10+2} = \frac{1}{12}\) → fails.

    So the correct equation is B.

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