等于双曲余弦
这是双曲正弦吧?
y=sinh(x)
y=[e^x-e^(-x)]/2
dy/dx=(1/2)*d[e^x-(e^-x)]/dx
=(1/2)*[e^x-e^(-x)*(-1)]
=[e^x+e^(-x)]/2
=cosh(x)