Solutions with detailed explanations to compass math test practice questions in sample 5.
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The solution of the equation - 3x + 7 = 4x - 12 falls bewteen what 2 numbers?
A) 3 and 3.5
B) 1 and 2.5
C) 2.1 and 3
D) 4 and 4.5
E) 19 and 7
Solution
We first solve the given equation
-3x + 7 = 4x - 12
-3x - 4x = -12 - 7
-7x = -19
x = 19/7 ≈ 2.71
The solution x = 19/7 is between 2.1 and 3. Answer C
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35x2 -11x - 6 is the product of 5x - 3 and
Solution
We are given one factor 5x - 3 and we need to find the second factor of 35x2 -11x - 6 as follows
35x2 -11x - 6 = (5x - 3)(7x + 2)
So 35x2 -11x - 6 is the product of 5x - 3 and 7x + 2
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For all real numbers x, y and z, 3√(64 x3 y z2) =
Solution
Let us rewrite the given expression as follows
3√(64 x3 y z2) = 641/3 (x3)1/3 y1/3 (z2)1/3
then simplify
= 4 x y1/3 z2/3
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For all x, 45 x4 - 115 x3 - 60 x2 =
A) 45 x2(x + 4)(x - 3)
B) 5 x2(9x + 4)(x - 3)
C) 5 x2(9x - 4)(x + 3)
D) 5 x2(9x - 4)(x - 3)
E) 45 x2(x - 4)(x + 3)
Solution
Factor 5 x2 out
45 x4 - 115 x3 - 60 x2 = 5x2 (9x2 -23x - 12)
We now factor the trinominal
= 5x2 (9x + 4)(x - 3)
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Which of the following is one of the factors of the polynomial -3x2 - 7x + 26?
A) x + 2
B) x + 1
C) -3x + 7
D) x - 2
E) 3x - 2
Solution
Factor -3x2 - 7x + 26
-3x2 - 7x + 26 = (-3x - 13)(x - 2)
x - 2 is a factor of the given expressions
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What is the product of the solutions of the equation 2x2 + x - 15?
Solution
The product of the solutions of a quadratic equation of the form ax2 + bx + c = 0 is equal to c / a. Hence the product of the solutions of the solutions of the given equation is equal to
-15/2
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If y = |x - 3|, what is the value of y2 when x = -2?
Solution
Evaluate y and then y2
y = |-2 - 3| = 5
y2 = 52 = 25
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The operation ||| is defined by x ||| y = x + y + xy. If -5 ||| y = -13, then y =
Solution
Use definition to express -5 ||| y in terms of y
-5 ||| y = (-5) + y + (-5)y = -5 + y - 5y = -5 - 4y
Use the fact that -5 ||| y = -13 to write an equation
-5 - 4y = - 13
Solve for y
y = 2
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A car uses 15 gallons of gaz to travel 300 miles. How many gallons are needed for this car to travel a distance of 430 miles?
Solution
Let us first find how many gallons are used to travel 1 mile
15 gallons / 300 miles = 1 /20 gallons per mile
The number of gallons needed for 430 miles is given by
(1 /20 gallons per mile)*(430 miles) = 21.5 gallons
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David has 200 books in his library. 30% of these books are about science. Of these books about science, 20% are about mathematics. How many math books does David have?
Solution
Number of science books is
30% of 200 = 30% * 200 = 60 books
Number of math books is
20% of 60 = 20% * 60 = 12 bokks.
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√32 √2 =
Solution
Use 32 = 2 * 16 and simplify
√32 √2 = √(2*16)√2
= √2 √16 √2
= 4 √2 √2 = 4 * 2 = 8
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If a = 3 and b = -1, then -3a2 - 2ab + b3
Solution
Substitute
-3a2 - 2ab + b3 = -3(3)2 - 2(3)(-1) + (-1)3
Simplify
= -3(9) + 6 - 1 = -27 + 6 - 1 = -22
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(-3x2 - x - 10) - (- 3x + 8)?
Solution
Multiply, group like terms and simplify
(-3x2 - x - 10) - (- 3x + 8) = -3x2 - x - 10 + 3x - 8)
= -3x2 + 2x - 18
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(4 - √5)(4 + √5) =
Solution
Expand and simplify
(4 - √5)(4 + √5) = 42 - √5 2 = 16 - 5 = 11
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In a standard (x,y) coordinate plane, the point (-2 , -6) is located
Solution
Both coordinates are negantive, therefore the point (-2 , -6) is located in quadrant III
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| -7 - 9 | =
Solution
Simplify as follows
| -7 - 9 | = |-16| = 16
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If the ratio of 7 to x is equal to 42/30, then x =
Solution
We are given
7 / x = 42 / 30
Solve for x
7 * 30 = 42 * x
x = 5
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If x = 1/3, then 4 x2 - 2x + 2 =
Solution
Substitute
4 x2 - 2x + 2 = 4 (1/3)2 - 2(1/3) + 2 =
Simplify using common denominator
4 * (1/9) - 2/3 + 2 = 4 / 9 - 6 / 9 + 18 /9 = 16 / 9
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Which equations corresponds to a line that is perpendicular to the line 2y + 3x = 6
A) y = -(2/3)x + 9
B) y = (3/2)x + 4
C) y = -(3/2)x - 5
D) y = 2/3
E) y = (2/3)x + 3
Solution
Write in slope intercept form and find the slope of given line
2y + 3x = 6
2y = -3x + 6
y = (-3/2) x + 2 , slope = - 3 / 2
Slope of line perpendicular to the given line is equal to
-1 / (-3/2) = 2 / 3
Hence line E) given by y = (2/3)x + 3
is perpendicular to the given line
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(√128) / 2 + (5√2) / 4 =
Solution
Use 128 = 2 * 64 to write
(√128) / 2 + (5√2) / 4 = (√(2*64)) / 2 + (5√2) / 4 =
= (√2 √64) / 2 + (5√2) / 4
= 8 √2 / 2 + 5√2 / 4
= 16 √2 / 4 + 5√2 / 4 = 21 √2 / 4
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