a/b-b/a-(a^+b^/ab)=(a^-b^)/ab-(a^+b^)/ab=-2b^/ab^=-2b/a因为9a^-4b^=0a/b=±2/3若a/b=2/3,则原式=-3若a/b=-2/3,则原式=3
9a^2-4b^2=09a^2=4b^2b^2/a^2=9/4所以b/a=±3/2a/b-b/a-(a^2+b^2/ab)通分=(a^2-b^2-a^2-b^2)/ab=-2b^2/ab=-2b/a=-2*(±3/2)=±3