Practicing Success
If x4 + \(\frac{1}{x^4}\) = 15127, the positive value of x - \(\frac{1}{x}\) is? |
9 11 13 18 |
11 |
x4 + \(\frac{1}{x^4}\) = 15127 x2 + \(\frac{1}{x^2}\) = \(\sqrt {15127 + 2}\) = 123 So, x - \(\frac{1}{x}\) = \(\sqrt {123 - 2}\) = 11 |