Algebrahard · Past Paper
If x + 1/x = 3, find the value of x^5 + 1/x^5.
A123
B243
C126
D110
✓ Correct Answer: A — 123
x^2+1/x^2=7. x^3+1/x^3=18. (x^2+1/x^2)(x^3+1/x^3) = x^5 + 1/x^5 + x + 1/x. 7*18 = x^5 + 1/x^5 + 3. 126-3=123.
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✓ Correct Answer: A — 123
x^2+1/x^2=7. x^3+1/x^3=18. (x^2+1/x^2)(x^3+1/x^3) = x^5 + 1/x^5 + x + 1/x. 7*18 = x^5 + 1/x^5 + 3. 126-3=123.
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