algebra (1 Viewer)

Mahan1 · Mar 6, 2017

If $\frac{1}{x} + x = A$ then find the below expression in terms of A
$x^{7}+ \frac{1}{x^{7}}$

1729 · Mar 6, 2017

Mahan1 said:
If $\frac{1}{x} + x = A$ then find the below expression in terms of A
$x^{7}+ \frac{1}{x^{7}}$

$$\noindent If $\frac{1}{x} + x = A$ then $x^2 - Ax + 1 =0$. Solve for $x$ and substitute into $x^7 + \frac{1}{x^7}$ to get $x^7 + \frac{1}{x^7} = \left(\frac{A \pm \sqrt{A^2-4}}{2}\right)^7 + \left(\frac{2}{A \pm \sqrt{A^2 - 4}}\right)^7$

BenHowe · Mar 6, 2017

This question was actually the last mcq in the mx2 paper last year... But A was -1 I think

algebra (1 Viewer)

Mahan1

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