АА Александр Абросимов 1) y = cos(5x) dy/dx = - 5*sin(5x), d2y/(dx)^2 = -25*cos(5x). 2) y = ln(4/x), dy/dx = - 4* [1/(4/x)]*x^(-2) = - 4x/[4*x^2] = - 1/x, d2y/(dx)^2 = x^(-2)