∫e^(k|x|)dx(x从负无穷大到正无穷大)=∫e^kxdx(x从0到正无穷大)+∫e^(-kx)dx(x从负无穷大到0)
=[1/ke^kx](x从0到正无穷大)-[1/ke(-kx)](x从负无穷大到0)
=1/klime^kx(x趋向于正无穷大)-1/k-[1/k-1/klime^(-kx)(x趋向于负无穷大)]=1
k
∫e^(k|x|)dx(x从负无穷大到正无穷大)=∫e^kxdx(x从0到正无穷大)+∫e^(-kx)dx(x从负无穷大到0)
=[1/ke^kx](x从0到正无穷大)-[1/ke(-kx)](x从负无穷大到0)
=1/klime^kx(x趋向于正无穷大)-1/k-[1/k-1/klime^(-kx)(x趋向于负无穷大)]=1
k