Practicing Success
If $x-\frac{1}{x}=\sqrt{77}$, then one of the values of $x^3+\frac{1}{x^3}$ is : |
$80 \sqrt{77}$ -702 $77 \sqrt{77}$ $3 \sqrt{77}$ |
-702 |
If x - \(\frac{1}{x}\) = n then then, x + \(\frac{1}{x}\) = \(\sqrt {n^2 + 4}\) If $x-\frac{1}{x}=\sqrt{77}$ x + \(\frac{1}{x}\) = \(\sqrt {77 + 4}\) = 9 If x + \(\frac{1}{x}\) = n then, $x^3 +\frac{1}{x^3}$ = n3 - 3 × n $x^3 +\frac{1}{x^3}$ = 93 - 3 × 9 = (+-) 702 |