Bluebook SAT Test SAT Exponents and Radicals Practice — Questions and Answers
Question 1: Which of the following is equivalent to x^(2/3)?
- ∛(x²) (Correct answer)
- x² ÷ x³
- √(x³)
- x^(3/2)
Correct answer: ∛(x²)
The rational exponent 2/3 means the cube root of x squared: x^(2/3) = ∛(x²).
Question 2: Simplify: (3x²y³)² × (2xy)³
- 72x⁷y⁹ (Correct answer)
- 72x⁷y⁸
- 36x⁷y⁹
- 54x⁷y⁹
Correct answer: 72x⁷y⁹
(3x²y³)² = 9x⁴y⁶ and (2xy)³ = 8x³y³. Product = 72x^(4+3)y^(6+3) = 72x⁷y⁹.
Question 3: What is the value of 27^(−2/3)?
- 1/9 (Correct answer)
- 9
- 1/27
- −9
Correct answer: 1/9
27^(2/3) = (∛27)² = 3² = 9. The negative exponent gives the reciprocal: 1/9.
Question 4: If 2^x = 32, what is the value of 2^(x−3)?
Correct answer: 4
2^x = 2^5 so x = 5. Then 2^(5−3) = 2² = 4.
Question 5: Simplify: √(50x⁴y²)
- 5x²y√2 (Correct answer)
- 5xy√2
- 10x²y
- 5x²√(2y)
Correct answer: 5x²y√2
√(50x⁴y²) = √(25·2·x⁴·y²) = 5x²y√2.
Question 6: Which expression is equivalent to (x^(1/2))(x^(1/3))?
- x^(1/6)
- x^(5/6) (Correct answer)
- x^(2/3)
- x^(1/3)
Correct answer: x^(5/6)
Add exponents: 1/2 + 1/3 = 3/6 + 2/6 = 5/6. Result is x^(5/6).
Question 7: What is the value of (8^(1/3) + 16^(1/2)) ÷ 4^(1/2)?
- 2.5
- 3 (Correct answer)
- 3.5
- 4
Correct answer: 3
8^(1/3) = 2, 16^(1/2) = 4, 4^(1/2) = 2. (2 + 4)/2 = 3.
Question 8: Which of the following equals 3^(x+2)?
- 3^x + 9
- 9 × 3^x (Correct answer)
- 3^x × 2
- 3^(2x)
Correct answer: 9 × 3^x
3^(x+2) = 3^x × 3² = 9 × 3^x.
Question 9: Simplify ∛54 in simplest radical form.
- 3∛2 (Correct answer)
- 3∛6
- 2∛7
- 6∛2
Correct answer: 3∛2
∛54 = ∛(27 × 2) = 3∛2.
Question 10: What is the value of x if √(x + 9) − √x = 1?
- 16 (Correct answer)
- 20
- 25
- 36
Correct answer: 16
Isolate: √(x+9) = √x + 1. Square: x + 9 = x + 2√x + 1 → 8 = 2√x → √x = 4 → x = 16.
Question 11: Simplify: (x²/y)³ ÷ (x/y²)²
- x⁴/y
- x⁴y (Correct answer)
- x⁴
- x⁴y⁻¹
Correct answer: x⁴y
(x²/y)³ = x⁶/y³ and (x/y²)² = x²/y⁴. Dividing: x⁶/y³ ÷ x²/y⁴ = x⁴y.
Question 12: Which of the following equals 5^(1/2) × 20^(1/2)?
- 2√5
- 5√2
- 10 (Correct answer)
- √100
Correct answer: 10
(5 × 20)^(1/2) = 100^(1/2) = 10.
Question 13: Determine the value of (−32)^(3/5).
Correct answer: −8
(−32)^(3/5) = (⁵√(−32))³ = (−2)³ = −8.
Question 14: Simplify: (a²b⁻¹)^3 × (a⁻¹b²)^2
- a⁴b (Correct answer)
- a⁴b⁻³
- a⁴b⁻¹
- a⁴
Correct answer: a⁴b
(a²b⁻¹)³ = a⁶b^(−3) and (a⁻¹b²)² = a^(−2)b⁴. Product = a^(6−2)b^(−3+4) = a⁴b.
Question 15: What is (2.5 × 10⁸) ÷ (5.0 × 10³) in scientific notation?
- 5.0 × 10⁴ (Correct answer)
- 5.0 × 10⁵
- 0.5 × 10⁶
- 2.5 × 10⁵
Correct answer: 5.0 × 10⁴
(2.5 ÷ 5.0) × 10^(8−3) = 0.5 × 10⁵ = 5.0 × 10⁴.
Question 16: If f(x) = x^(2/3) and f(k) = 4, what is k?
Correct answer: 8
k^(2/3) = 4 → k = 4^(3/2) = (√4)³ = 8.
Question 17: Which is greater: 2^30 or 3^20?
- 2^30
- 3^20 (Correct answer)
- They are equal
- Cannot be determined
Correct answer: 3^20
2^30 = (2³)^10 = 8^10 and 3^20 = (3²)^10 = 9^10. Since 9 > 8, we have 3^20 > 2^30.
Question 18: Simplify √(x² + 6x + 9) for x ≥ 0.
- x + 3 (Correct answer)
- |x + 3|
- x + √3
- x − 3
Correct answer: x + 3
x² + 6x + 9 = (x+3)². For x ≥ 0, x+3 > 0, so √((x+3)²) = x+3.
Question 19: What is the simplified form of (27/8)^(2/3)?
- 3/2
- 9/4 (Correct answer)
- 3/4
- 4/9
Correct answer: 9/4
(27/8)^(2/3) = (∛(27/8))² = (3/2)² = 9/4.
Question 20: Solve: 2^(3x−1) = 16
- x = 5/3 (Correct answer)
- x = 4/3
- x = 2
- x = 1
Correct answer: x = 5/3
16 = 2⁴, so 3x − 1 = 4 → x = 5/3.
Question 21: Which of the following is equivalent to x^(3/4) ÷ x^(1/4)?
- x^(3/16)
- x^(1/2) (Correct answer)
- x^(4/4)
- x³
Correct answer: x^(1/2)
x^(3/4 − 1/4) = x^(2/4) = x^(1/2).
Question 22: Which of the following equals (a⁴ × b⁶)^(1/2)?
- a²b³ (Correct answer)
- a²b²
- a⁴b³
- a³b²
Correct answer: a²b³
(a⁴b⁶)^(1/2) = a^(4/2) × b^(6/2) = a²b³.
Question 23: An exponential function is y = 3 × 2^x. What is the percent increase from x = 2 to x = 3?
- 50%
- 100% (Correct answer)
- 150%
- 200%
Correct answer: 100%
At x=2: y=12; at x=3: y=24. Percent increase = (24−12)/12 × 100 = 100%.
Question 24: What is the value of 4^(3/2) + 8^(2/3)?
- 10
- 11
- 12 (Correct answer)
- 14
Correct answer: 12
4^(3/2) = (√4)³ = 8 and 8^(2/3) = (∛8)² = 4. Sum = 8 + 4 = 12.
Question 25: Simplify: (3^n × 9^n) / 27^n
- 1 (Correct answer)
- 3^n
- 9^n
- 27^n
Correct answer: 1
9^n = 3^(2n) and 27^n = 3^(3n). Numerator = 3^n × 3^(2n) = 3^(3n). Ratio = 3^(3n)/3^(3n) = 1.
Question 26: Solve: √(2x − 3) = √(x + 7)
- x = 5
- x = 8
- x = 10 (Correct answer)
- x = 14
Correct answer: x = 10
Square both sides: 2x − 3 = x + 7 → x = 10. Verify: √17 = √17 ✓.
Question 27: What is the approximate value of 5^(1.5)?
- 7.07
- 9.66
- 11.18 (Correct answer)
- 12.50
Correct answer: 11.18
5^(1.5) = 5^(3/2) = (√5)³ ≈ (2.236)³ ≈ 11.18.
Question 28: Which expression is equivalent to (√x + √y)²?
- x + y
- x + y + 2xy
- x + y + √(xy)
- x + y + 2√(xy) (Correct answer)
Correct answer: x + y + 2√(xy)
(√x + √y)² = x + 2√(xy) + y = x + y + 2√(xy).