y=x^3-4x^2+100x跪求步骤三个分开，一个一个来d(x^3)/dx=3x^2d(x^2)/dx=2xdx/dx=1所以dy/dx=d(x^3)/dx-4*[d(x^2)/dx]+100*(dx/dx)dy=d(x^3)-4*d(x^2)+100*dx=d(x^3-4x^2+100x )y=x^3-4x^2+100x