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If x2 - 7x - 1= 0 and x > 1, then the value of x3 - \(\frac{1}{x^3}\) will be: |
322 362 343 364 |
364 |
If x2 - 7x - 1= 0 Divide by x on both sides, x - \(\frac{1}{x}\) = 7 x3 - \(\frac{1}{x^3}\) = 73 + 3 × 7 = 364
Note - if x - \(\frac{1}{x}\) = a then x3 - \(\frac{1}{x^3}\) = a3 + 3a |
