Question

当a-b分之a+b=2时,求代数式4（a-b）分之3（a+b）减去2（a+b）分之a-b的值

Answer 1

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

取倒数

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

原式=(3/4)[(a+b/(a-b)]-(1/2)[(a-b)/(a+b)]

=3/2-1/4

=4分之5