Jawabanmu

2014-09-11T18:38:40+07:00
1. 7a+7ab-3b-3ab=4ab+7a-3b
3. = x (x-y) + y(x+y) / (x+y)(x-y)
= x^2-xy+xy+y^2 / x^2+y^2
=x^2+y^2 / x^2-y^2