Algebrahard · Past Paper
If x^2 - 5x + 1 = 0, find the value of x^2 + 1/x^2.
A23
B25
C27
D21
✓ Correct Answer: A — 23
Divide by x: x - 5 + 1/x = 0 → x + 1/x = 5. (x+1/x)^2 = 25 → x^2 + 1/x^2 + 2 = 25 → x^2 + 1/x^2 = 23.
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✓ Correct Answer: A — 23
Divide by x: x - 5 + 1/x = 0 → x + 1/x = 5. (x+1/x)^2 = 25 → x^2 + 1/x^2 + 2 = 25 → x^2 + 1/x^2 = 23.
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