$${ x }^{ 6 } = { \left(8-7x \right) }^{ 2 }$$
$x=1$
$x = -\frac{9 ^ {\frac{2}{3}} {(\sqrt[3]{\sqrt{267} + 36} + \sqrt[3]{36 - \sqrt{267}})}}{9} \approx -3.095823999$
