x的m-1次方分之x的m+1次方+x的m-1次方
=(x的m次方*x+x的m次方*x的-1次方)/(x的m次方*x的-1次方)
=x的m次方(x+x的-1次方)/(x的m次方*x的-1次方)
=(x+1/x)/(1/x)
=[(x²+1)/x]/(1/x)
=x²+1