f(x)=(2+x^2)\x^3. Найдите f`(-1\sqrt2)

f'(x)= 2x*x³-(2+x²)*3x² / x⁶ = 2x⁴-6x²-3x⁴/x⁶=-6x²-x⁴/x⁶ = -6-x²/x⁴

f'(-1/√2) = -6-1/2 / 1/4 = -6 1/2  *4 =-  13/2 *4 =  -26