e^x^4=y,e^x=y^(1/4);
e^xdx=y^(-3/4)dy/4=y^(1/4)dx
dx=y^(-3/4)dy/[4y^(1/4)]=dy(/4y)
∫e^x^4dx=∫ydy/(4y)=4y+C=4e^x^4+C最后一步∫e^x^4dx=∫ydy/(4y)不是应该等于y/4+c吗最后一步∫e^x^4dx=∫ydy/(4y)是应该等于y/4+c