1. Show that y=2*e^(5x)+4x is a solution to the differential equation y'-5y=4-20x2. Determine eventual max, min and saddle points in the function f(x)=x^3-6x^2-15x+243. Determine the biggest and smallest value of teh function y=cos(x)+x*sin(x) in the interval 0=x=2*pi. An exact answer is needed.