[(a-b)/(a+b)]×[(a^4-a²b²)/(a²-ab)]=[(a-b)/(a+b)]×[a²(a²-b²)/a(a-b)]=[(a-b)/(a+b)]×[a²(a+b)(a-b)/a(a-b)]=[(a-b)/(a+b)]×[a²(a+b)/a]=[a²(a+b)(a-b)]/[a(a+b...