Answer
$x = 2$
Work Step by Step
$2.5x^{8} - 3000 = - 2360$
$2.5x^{8} = -2360 + 3000$
$2.5x^{8} = 640$
$x^{8} = 256$
$x^{8} = 256^{\frac{1}{8}}$
$x = 2$
Check:
$2.5(2)^{8} - 3000 \overset{?}{=} - 2360$
$2.5(256) - 3000 \overset{?}{=} - 2360$
$640 - 3000 \overset{?}{=} - 2360$
$-2360 = -2360$