Question

当a+b 分之 a-b=二分之一时,求代数式3（a-b）分之a+b - 2（a+b）分之a-b的值.

Answer 1

∵(a-b)/(a+b)=½

∴(a+b)/(a-b)=2

(a+b)/[3(a-b)]-(a-b)/[2(a+b)]

=(1/3)[(a+b)/(a-b)]-(½)[(a-b)/(a+b)]

=(1/3)×2-(½)×(½)

=(2/3)-(¼)

=5/12