x=linspace( -4, 4, 100 );plot(x,x.^3+3*x.^2+3*x+1); grid on
x= linspace( -4, 4, 100 );plot(x,x.*exp(x-1)-x-exp(x-1)+1);grid on
x = linspace( 0, 4, 1500 );plot(x,x.^2-4*x+4); grid on
