解法一：运用公式(u/v)'=(u'v-uv')/v²解[1/(x+1)]'=[1'·(x+1)-1·(x+1)']/(x+1)²=（0-1·1)/(x+1)²=-1/(x+1)²解法二：运用公式(xⁿ)'=nxⁿ⁻¹解[1/(x+1)]'=(-1)·(x+1)'/(x+1)²=-1/(x+1)²
