решите уравнение log2 8/x-log2*√2x=- 0.5

log2 8 - log2 x - (log2 2^1/2 + log2 x^1/2) = -0.5
3 - log2 x - 1/2 - 1/2log2 x = -1/2
-3/2log2 x = -3
log2 x = -3 : (-3/2) = -3 * (-2/3)
log2 x = 2
x = 2^2
x = 4

Вроде так