Question

若ab=1,则a/（a+1）+b/（b+1）的值是

Answer 1

=a/(a+1)+b/(b+1)

=a(b+1)/(a+1)(b+1)+b(a+1)/(a+1)(b+1)

=(ab+a+ab+b)/(a+1)(b+1)

=(2ab+a+b)/(ab+a+b+1)

=(2+a+b)/(a+b+2)

=1