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If x2 - 3x - 1= 0 and x > 1, then the value of x3 - \(\frac{1}{x^3}\) will be: |
18 24 45 36 |
36 |
If x2 - 3x - 1= 0 Divide by x on both sides, x - \(\frac{1}{x}\) = 3 x3 - \(\frac{1}{x^3}\) = 33 + 3 × 3 = 36
Note - if x - \(\frac{1}{x}\) = a then x3 - \(\frac{1}{x^3}\) = a3 + 3a |
