Question

Найдите производную функции . $fx=\frac{7-x^3}{5+x^{2}} , x0=-1$  

Answer 1

$f(x)=\frac{7-x^3}{5+x^{2}} \\ \\ f'(x)= \frac{(7-x^3)'(5+x^2)-(5+x^2)'(7-x^3)}{(5+x^2)^2} = \\ \\ \frac{-3x^2(5+x^2)-2x(7-x^3)}{(5+x^2)^2} = \frac{-3x^4-15x^2-14x+2x^4}{(5+x^2)^2} = \\ \\ \frac{-x^4-15x^2-14x}{(5+x^2)^2} =- \frac{x^4+15x^2+14x}{(5+x^2)^2} \\ \\ f'(-1)=- \frac{1+15-14}{(5+1)^2} =- \frac{2}{36} =- \frac{1}{18}$