Question

[ (a/a²-b²) - (1/a+b) ] × (b/b-a)

Answer 1

后面是÷b/(b-a)吧
原式=[a/(a+b)(a-b)-(a-b)/(a+b)(a-b)]÷[-b/(a-b)]
=b/(a+b)(a-b)×[-（a-b)/b]
=-1/(a+b)

Answer 2

题目应该是[ a/(a²-b²) - 1/(a+b) ] × b/(b-a)
=[ a/(a²-b²) - (a-b)/(a+b)(a-b) ] × b/(b-a)
=b/(a+b)(a-b)× b/(b-a)
=-b^2/(a+b)(a-b)^2