Question

Помогите с математикой)

Answer 1

$f(x)= frac{x^2-1}{x^2+1} \\f'(x)= frac{2x(x^2+1)-2x(x^2-1)}{(x^2+1)^2} = frac{4x}{(x^2+1)^2} \\f'(1)= frac{4}{(1+1)^2} =1$