Rules of Exponents: Questions and Step-by-Step Solutions - Grade 9

This page is designed to help students, parents, and teachers master the properties of exponents through carefully selected questions and detailed step-by-step solutions available immediately under each question block.

The exponential form is a convenient way to write long, repeated multiplications of the same number by itself:

\[ \underbrace{ a \cdot a \cdot a \dots a}_{ n \text{ times} } = a^n \]

Here, \( a \) is called the base (a real number) and \( n \) is called the exponent (an integer). The expression \( a^n \) is read as "\(a\) to the power of \(n\)." Understanding these rules is a critical stepping stone for advanced algebra and calculus.

Rules and Properties of Exponents

Review these fundamental properties before attempting the questions below:

# Rule Name Definition Examples
1 Exponent Form \( \underbrace{ a \cdot a \cdot a \dots a}_{ n \text{ times} } = a^n \) \( 4 \cdot 4 \cdot 4 \cdot 4 \cdot 4 = 4^5 \)
\( 2^3 = 2 \cdot 2 \cdot 2 = 8 \)
2 Negative Exponent \( a^{-n} = \dfrac{1}{a^n} \)  or  \( a^{n} = \dfrac{1}{a^{-n}} \) \( 3^{-4} = \dfrac{1}{3^4} \)
\( 5^{-2} = \dfrac{1}{5^2} \)
3 Product Rule (Same Base) \( a^m \cdot a^n = a^{m+n} \) \( 2^4 \cdot 2^6 = 2^{4+6} = 2^{10} \)
\( 3^{2+6} = 3^2 \cdot 3^6 \)
4 Product Rule (Same Exponent) \( a^m \cdot b^m = (a \cdot b)^m \) \( 2^5 \cdot 3^5 = (2 \cdot 3)^5 = 6^5 \)
\( (4 \cdot 3)^2 = 4^2 \cdot 3^2 \)
5 Quotient Rule (Same Base) \( \dfrac{a^m}{a^n} = a^{m - n} \) \( \dfrac{2^6}{2^4} = 2^{6-4} = 2^{2} \)
\( 3^{5-2} = \dfrac{3^5}{3^2} \)
6 Quotient Rule (Same Exponent) \( \left( \dfrac{a}{b} \right)^m = \dfrac{a^m}{b^m} \) \( \left( \dfrac{3}{5} \right)^4 = \dfrac{3^4}{5^4} \)
\( \dfrac{4^2}{5^2} = \left( \dfrac{4}{5} \right)^2 \)
7 Quotient Rule (Negative Exponent) \( \left( \dfrac{a}{b} \right)^{-m} = \dfrac{b^m}{a^m} \) \( \left( \dfrac{3}{5} \right)^{-2} = \dfrac{5^2}{3^2} \)
8 Power Rule \( (a^n)^m = a^{n \cdot m} \) \( (2^3)^4 = 2^{3\cdot4} = 2^{12} \)
\( 3^{4 \cdot 5} = (3^4)^5 = (3^5)^4 \)
9 Zero Exponent Rule \( a^0 = 1 \)   (for \(a \neq 0\)) \( 10000000^0 = 1 \)
Note: \( \color{red}{0^0 \text{ is undefined}} \)
10 Exponent One Rule \( a^1 = a \) \( 45^1 = 45 \)
\( 100 = 100^1 \)
11 Base One Rule \( 1^n = 1 \) \( 1^{230} = 1 \)
\( 1^{-100} = 1 \)
12 Negative One Base Rule \( (-1)^n = \begin{cases} 1, & \text{if } n \text{ is even} \\ -1, & \text{if } n \text{ is odd} \end{cases} \) \( (-1)^{19} = -1 \)
\( (-1)^{18} = 1 \)

Practice Questions & Solutions

Instructions: Try to solve all the following questions without using a calculator before expanding the solutions block.

  1. Evaluate the following expressions:
    1. \( 1^1 \)
    2. \( 2^3 \)
    3. \( (-2)^2 \)
    4. \( (-2)^3 \)
    5. \( 3^4 \)
    6. \( 4^2 \)
    7. \( 2^5 \)
    8. \( 5^2 \)
    9. \( (-1)^6 \)
    10. \( 7^2 \)
    11. \( (-9)^2 \)
    12. \( 3^3 \)
    13. \( 10^2 \)
    14. \( 10^3 \)
    15. \( 0.1^3 \)
    View Step-by-Step Solutions for Q1
    1. \( 1^1 = 1 \)
    2. \( 2^3 = 2 \cdot 2 \cdot 2 = 8 \)
    3. \( (-2)^2 = (-2) \cdot (-2) = 4 \)
    4. \( (-2)^3 = (-2) \cdot (-2) \cdot (-2) = -8 \)
    5. \( 3^4 = 3 \cdot 3 \cdot 3 \cdot 3 = 81 \)
    6. \( 4^2 = 4 \cdot 4 = 16 \)
    7. \( 2^5 = 2 \cdot 2 \cdot 2 \cdot 2 \cdot 2 = 32 \)
    8. \( 5^2 = 5 \cdot 5 = 25 \)
    9. \( (-1)^6 = 1 \) (Even power of negative one)
    10. \( 7^2 = 7 \cdot 7 = 49 \)
    11. \( (-9)^2 = (-9) \cdot (-9) = 81 \)
    12. \( 3^3 = 3 \cdot 3 \cdot 3 = 27 \)
    13. \( 10^2 = 10 \cdot 10 = 100 \)
    14. \( 10^3 = 10 \cdot 10 \cdot 10 = 1000 \)
    15. \( 0.1^3 = 0.1 \cdot 0.1 \cdot 0.1 = 0.001 \)
  2. Write the following numbers in exponential form with an exponent not equal to \( 1 \):
    (There might be more than one correct answer)
    1. \( 0 \)
    2. \( 1 \)
    3. \( 4 \)
    4. \( 8 \)
    5. \( 9 \)
    6. \( 16 \)
    7. \( 25 \)
    8. \( 32 \)
    9. \( 49 \)
    10. \( 64 \)
    11. \( 81 \)
    12. \( 100 \)
    13. \( -27 \)
    14. \( -8 \)
    15. \( -64 \)
    View Step-by-Step Solutions for Q2
    1. \( 0 = 0^2 = 0^3 = 0^4 \dots \)
      (Many possible answers. Note: \(0^0\) is undefined)
    2. \( 1 = 1^0 = 1^2 = 1^3 \dots \)
      (Many possible answers)
    3. \( 4 = 2^2 = (-2)^2 \)
    4. \( 8 = 2^3 \)
    5. \( 9 = 3^2 = (-3)^2 \)
    6. \( 16 = 2^4 = 4^2 = (-2)^4 = (-4)^2 \)
    7. \( 25 = 5^2 = (-5)^2 \)
    8. \( 32 = 2^5 \)
    9. \( 49 = 7^2 = (-7)^2 \)
    10. \( 64 = 8^2 = 4^3 = (-8)^2 \)
    11. \( 81 = 9^2 = (-9)^2 \)
    12. \( 100 = 10^2 = (-10)^2 \)
    13. \( -27 = (-3)^3 \)
    14. \( -8 = (-2)^3 \)
    15. \( -64 = (-4)^3 \)
  3. Use the rules of exponents to evaluate the following expressions:
    1. \( 120^0 \)
    2. \( 2^{-3} \)
    3. \( 2^{-3} \cdot 2^6 \)
    4. \( 2^3 \cdot 3^3 \)
    5. \( \dfrac{3^{10}}{3^8} \)
    6. \( 4^{-1} \)
    7. \( \dfrac{8^3}{4^3} \)
    8. \( \dfrac{100^3}{10^3} \)
    9. \( (2^2)^2 \)
    10. \( (1^3)^{25} \)
    11. \( ((-1)^2)^{20} \)
    12. \( - 2^{-2} \)
    13. \( ((-1)^{-1})^{-1} \)
    14. \( \left(\dfrac{100}{10}\right)^{-2} \)
    15. \( \left(\dfrac{10}{1000}\right)^{-2} \)
    View Step-by-Step Solutions for Q3
    1. \( 120^0 = 1 \) (Rule 9: Any non-zero number to power 0 is 1)
    2. \( 2^{-3} = \dfrac{1}{2^3} = \dfrac{1}{8} = 0.125 \) (Rule 2)
    3. \( 2^{-3} \cdot 2^6 = 2^{-3+6} = 2^3 = 8 \) (Rule 3)
    4. \( 2^3 \cdot 3^3 = (2 \cdot 3)^3 = 6^3 = 216 \) (Rule 4)
    5. \( \dfrac{3^{10}}{3^8} = 3^{10-8} = 3^2 = 9 \) (Rule 5)
    6. \( 4^{-1} = \dfrac{1}{4^1} = \dfrac{1}{4} = 0.25 \) (Rule 2)
    7. \( \dfrac{8^3}{4^3} = \left(\dfrac{8}{4}\right)^3 = 2^3 = 8 \) (Rule 6)
    8. \( \dfrac{100^3}{10^3} = \left(\dfrac{100}{10}\right)^3 = 10^3 = 1000 \) (Rule 6)
    9. \( (2^2)^2 = 2^{2 \cdot 2} = 2^4 = 16 \) (Rule 8)
    10. \( (1^3)^{25} = 1^{3 \cdot 25} = 1^{75} = 1 \) (Rules 8 and 11)
    11. \( ((-1)^2)^{20} = (-1)^{2 \cdot 20} = (-1)^{40} = 1 \) (Rules 8 and 12)
    12. \( -2^{-2} = - \dfrac{1}{2^2} = - \dfrac{1}{4} = -0.25 \) (Rule 2)
    13. \( ((-1)^{-1})^{-1} = (-1)^{(-1) \cdot (-1)} = (-1)^1 = -1 \) (Rules 8 and 12)
    14. \( \left(\dfrac{100}{10}\right)^{-2} = \left(\dfrac{10}{100}\right)^2 = 0.1^2 = 0.01 \) (Rule 7)
    15. \( \left(\dfrac{10}{1000}\right)^{-2} = \left(\dfrac{1000}{10}\right)^2 = 100^2 = 10000 \) (Rule 7)
  4. Simplify and write the following expressions with a single positive exponent if possible:
    1. \( 3^2 \cdot 3^8 \)
    2. \( \dfrac{2^5}{2^2} \)
    3. \( \left(3^5\right)^2 \)
    4. \( 6^4 \cdot \dfrac{6^5}{6^2} \)
    5. \( (-7)^2 \cdot (-7)^3 \)
    6. \( (5^2)^2 \cdot (5^3)^3 \cdot 5 \)
    7. \( x^{-1} \cdot x^3 \)
    8. \( \dfrac{a^5}{a^2} \)
    9. \( \dfrac{a^2}{a^7} \)
    10. \( 2^x \cdot 4^3 \cdot 2^y \)
    11. \( (3^{-1})^x \)
    12. \( 3^x \cdot 9^x \)
    13. \( \dfrac{a^x}{a^4} \cdot a^6 \)
    View Step-by-Step Solutions for Q4
    1. \( 3^2 \cdot 3^8 = 3^{2+8} = 3^{10} \) (Rule 3)
    2. \( \dfrac{2^5}{2^2} = 2^{5-2} = 2^3 \) (Rule 5)
    3. \( \left(3^5\right)^2 = 3^{5 \cdot 2} = 3^{10} \) (Rule 8)
    4. \( 6^4 \cdot \dfrac{6^5}{6^2} = 6^4 \cdot 6^{5-2} = 6^4 \cdot 6^3 = 6^{4+3} = 6^7 \) (Rules 5 and 3)
    5. \( (-7)^2 \cdot (-7)^3 = (-7)^{2+3} = (-7)^5 \) (Rule 3)
    6. \( (5^2)^2 \cdot (5^3)^3 \cdot 5 = 5^4 \cdot 5^9 \cdot 5^1 = 5^{4+9+1} = 5^{14} \) (Rules 8 and 3)
    7. \( x^{-1} x^3 = x^{-1+3} = x^2 \) (Rule 3)
    8. \( \dfrac{a^5}{a^2} = a^{5-2} = a^3 \) (Rule 5)
    9. \( \dfrac{a^2}{a^7} = a^{2-7} = a^{-5} = \dfrac{1}{a^5} \) (Rules 5 and 2)
    10. \( 2^x \cdot 4^3 \cdot 2^y \): Write \( 4 \) as \( 2^2 \), so \( (2^2)^3 = 2^6 \). Then, \( 2^x \cdot 2^6 \cdot 2^y = 2^{x+6+y} \)
    11. \( (3^{-1})^x = 3^{-x} = \dfrac{1}{3^x} \) (Rules 8 and 2)
    12. \( 3^x \cdot 9^x = (3 \cdot 9)^x = 27^x \) (Rule 4)
    13. \( \dfrac{a^x}{a^4} \cdot a^6 = a^{x-4} \cdot a^6 = a^{x-4+6} = a^{x+2} \) (Rules 5 and 3)
  5. Simplify the following algebraic expressions:
    1. \( a^2 \cdot \dfrac{a^5}{a^2} \)
    2. \( \left (\dfrac{3x}{x} \right)^3 \)
    3. \( (2^2)^2 \)
    4. \( \dfrac{1}{4} \cdot \left (\dfrac{2x}{x} \right)^2 \)
    5. \( \dfrac{y^4 x^3}{x^2y^2} \)
    6. \( \dfrac{x^2}{4y^2} \cdot \left (\dfrac{8y}{x} \right)^2 \)
    7. \( (-6a)^2 \cdot (a^2 + 1)^0 \)
    View Step-by-Step Solutions for Q5
    1. \( a^2 \cdot \dfrac{a^5}{a^2} \)
      Apply Quotient Rule: \( a^2 \cdot a^{5-2} = a^2 \cdot a^3 = a^{2+3} = a^5 \)
    2. \( \left (\dfrac{3x}{x} \right)^3 \)
      Simplify by cancelling \( x \) inside the bracket: \( \left(\dfrac{3}{1}\right)^3 = 3^3 = 27 \)
    3. \( (2^2)^2 \)
      Evaluate \( 2^2 \) inside the bracket first: \( 4^2 = 16 \)
    4. \( \dfrac{1}{4} \cdot \left (\dfrac{2x}{x} \right)^2 \)
      Cancel \( x \) inside the bracket: \( \dfrac{1}{4} \cdot 2^2 = \dfrac{1}{4} \cdot 4 = 1 \)
    5. \( \dfrac{y^4 x^3}{x^2 y^2} \)
      Group by variable: \( \left(\dfrac{x^3}{x^2}\right) \cdot \left(\dfrac{y^4}{y^2}\right) = x^{3-2} \cdot y^{4-2} = xy^2 \)
    6. \( \dfrac{x^2}{4y^2} \cdot \left (\dfrac{8y}{x} \right)^2 \)
      Apply Rule 6 to the second term: \( \dfrac{x^2}{4y^2} \cdot \dfrac{(8y)^2}{x^2} = \dfrac{x^2}{4y^2} \cdot \dfrac{64y^2}{x^2} \)
      Cancel like terms (\(x^2\) and \(y^2\)): \( \dfrac{64}{4} = 16 \)
    7. \( (-6a)^2 \cdot (a^2 + 1)^0 \)
      Use Rule 9 to evaluate \( (a^2 + 1)^0 = 1 \). Then apply Rule 4 to \( (-6a)^2 \): \( (-6)^2 \cdot a^2 \cdot 1 = 36a^2 \)

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