计算①(1/a-b)-(1/a+b)+(2b/a^2+b^2)

问题描述:

计算①(1/a-b)-(1/a+b)+(2b/a^2+b^2)

=(a+b)/(a²-b²)-(a-b)/(a²-b²)+2b/(a²+b²)=2b/(a²-b²)-2b/(a²+b²)=2b[(a²+b²)-(a²-b²)]/(a^4-b^4)=4b³/(a^4-b^4)