问题补充:
y=e的负x 次方*cosx ,求dy
答案:
y=-e^(-x)cosx-e^(-x)sinx=-e^(-x)(cosx+sinx)
dy=ydx=[-e^(-x)(cosx+sinx)]dx
======以下答案可供参考======
供参考答案1:
dy=-[e^(-x)]cosxdx-[e^(-x)]sinxdx
=-[e^(-x)](cosx+sinx)dx
供参考答案2:
dy=[e^(-x)(-1)cosx+e^(-x)(-sinx)]dx.
=-[e^(-x)cosx+sinx]dx.
供参考答案3:
如图所示: y=e的负x 次方*cosx ,求dy(图1)答案网 答案网