If x + 1/x = 3, then what is the value of x³ + 1/x³?
- 18
- 20
- 21
- None of these
Explanation
Given x + 1/x = 3
To find x³ + 1/x³:
(x + 1/x)³ = x³ + 3(x²)(1/x) + 3(x)(1/x)² + 1/x³
= x³ + 3x + 3/x + 1/x³
= x³ + 1/x³ + 3(x + 1/x)
(x + 1/x)³ = x³ + 1/x³ + 3(3)
27 = x³ + 1/x³ + 9
x³ + 1/x³ = 27 - 9
= 18
Related MCQs
- 2/x + 12/(x +5)
- 3/x + 22/(x +5)
- 4/x + 16/(x +5)
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
- 4
- 5
- 6
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
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