Question

For what values of $x$, the numbers $-\frac{2}{7},x,-\frac{2}{7}$ are in $G.P$?

Answer 1

If any three numbers are in G.P then we can assume them as $\frac{a}{r},a,ar$ .

$r^2=1⟹r=\pm 1⟹x=\pm \frac{2}{7}$