(a-b)分之1-(a+b)分之1+(a^2+b^2)分之2b=(a+b)/(a²-b²)-(a-b)/(a²-b²)+2b/(a²+b²)=(a+b-a+b)/(a²-b²)+2b/(a²+b²)=2b[1/(a²-b²)+1/(a²+b²)]=...