у' = (cos 6x)' * ln 8x + cos 6x * (ln 8x)' = -6 * sin 6x * ln 8x + cos 6x * 1/(8x) * 8 =
-6 * sin 6x * ln 8x + cos 6x / x
у' = (cos 6x)' * ln 8x + cos 6x * (ln 8x)' = -6 * sin 6x * ln 8x + cos 6x * 1/(8x) * 8 =
-6 * sin 6x * ln 8x + cos 6x / x