А) (x^(5/6) + 6x)' = 5/6 * x^(5/6 - 1) + 6 = 5/6 * x^(-1/6) + 6
б) (x^(2/5))' = 0.4*x^(-3/5)
в) (x^(-8/8) * (sqrtx -3))' = (x^(-1)*(x^(1/2) - 3))' = (x^(-1/2) - 3*x^(-1))' = -0.5*x^(-3/2) + 3*x^(-2)
г) ((7-6x)^(1/3) )' = 1/3 * (7-6x)^(1/3 - 1) * (-6) = -2*(7-6x)^(-2/3)