Algebra 2 Practice Test: Rational Exponents and nth Roots
- Rational Exponents and nth Roots
- 10 questions
- 13 minutes
These 10 questions cover expressions like 27 to the 2/3 power and their radical forms. Tip: the denominator of the exponent is the root, and the numerator is the power.
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Question 1
What is the value of 272/3?
Correct answer: B
Take the cube root first, then square: 3√(27) = 3 and 32 = 9. The answer 18 multiplies 27 by 23 instead.
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Question 2
What is the value of 16−3/4?
Correct answer: C
4√(16) = 2 and 23 = 8; the negative exponent means the reciprocal, so the value is 18. A negative exponent never makes the result negative.
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Question 3
Which expression is equal to x3/5?
Correct answer: C
In xm/n the denominator n is the index of the root and the numerator m is the power: x3/5 = 5√(x3).
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Question 4
Simplify x1/2 · x1/3.
Correct answer: D
When multiplying powers with the same base, add the exponents: 12 + 13 = 56. Multiplying the exponents gives the trap x1/6.
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Question 5
Simplify (8x6)1/3.
Correct answer: A
Apply the exponent to each factor: 81/3 = 2 and (x6)1/3 = x2. The power must also act on the 8.
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Question 6
Solve x3/2 = 64.
Correct answer: B
Raise both sides to the 23 power: x = 642/3 = (3√(64))2 = 42 = 16. The answer 512 raises 64 to the 32 power instead.
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Question 7
What is the real value of 3√(−125)?
Correct answer: B
(−5)3 = −125, so the real cube root is −5. Odd roots of negative numbers are real; only even roots of negatives are not.
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Question 8
For x > 0, which expression equals 4√(32x8)?
Correct answer: A
32 = 16 · 2 and 4√(16) = 2; also 4√(x8) = x2. So the expression is 2x24√(2). Taking half of the exponent 8 gives the wrong x4.
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Question 9
Solve 2x3/4 = 54.
Correct answer: C
Divide by 2: x3/4 = 27. Raise to the 43 power: x = 274/3 = 34 = 81. Check: 813/4 = 33 = 27.
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Question 10
For x > 0, which expression equals x−1/2?
Correct answer: D
The exponent 12 means a square root, and the negative sign means a reciprocal: x−1/2 = 1x.
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