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Exponents and Logarithms · Ages 16–17

Evaluating Fractional and Negative Exponents

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Designed for 11th grade math students. Simplify each expression without using a calculator by rewriting powers as roots.

  1. Evaluate 25^(1/2).

  2. Evaluate 64^(1/3).

  3. Evaluate 8^(2/3).

  4. Evaluate 36^(-1/2).

  5. Evaluate 32^(3/5).

  6. Evaluate 81^(-3/4).

  7. Evaluate (4/9)^(-3/2).

  8. Simplify (x^(2/3)) * (x^(4/3)) into a single power of x.

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Evaluating Fractional and Negative Exponents

Answer key

  1. Evaluate 25^(1/2).

    5 (Take the square root of 25).

  2. Evaluate 64^(1/3).

    4 (Take the cube root of 64).

  3. Evaluate 8^(2/3).

    4 (The cube root of 8 is 2, and 2 squared is 4).

  4. Evaluate 36^(-1/2).

    1/6 (The square root of 36 is 6, and the negative exponent inverts it to 1/6).

  5. Evaluate 32^(3/5).

    8 (The fifth root of 32 is 2, and 2 cubed is 8).

  6. Evaluate 81^(-3/4).

    1/27 (The fourth root of 81 is 3, 3 cubed is 27, and the negative exponent makes it 1/27).

  7. Evaluate (4/9)^(-3/2).

    27/8 (Invert the fraction to 9/4, take the square root to get 3/2, then cube both numbers to get 27/8).

  8. Simplify (x^(2/3)) * (x^(4/3)) into a single power of x.

    x^2 (Add exponents: 2/3 + 4/3 = 6/3 = 2).