y=e^x/x^5=y=e^x*x^(-5)
y'=e^x*x^(-5)-5e^x*x^(-6)
=e^x(x-5)/x^6
dy=[e^x(x-5)/x^6]dxdy=x^5de^x-e^xdx^5 / x^10 =x^5e^xdx-5x^4e^xdx / x^10那是用商的导数，结果是一样的[x^5e^xdx-5x^4e^xdx ]/ x^10=[e^x/x^5-5e^x/ x^6]dx