Algebra & Equations · Question 13 · Hard
If x + 1/x = 5, what is the value of x³ + 1/x³?
- 115
- 110
- 140
- 125
Answer and explanation
Answer: B. 110
Explanation: (x + 1/x)³ = x³ + 1/x³ + 3(x + 1/x). So 125 = x³ + 1/x³ + 15, giving x³ + 1/x³ = 110.
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