Question

Помогите решить а²в²-(ав-7)²= ?

Answer 1

a²b²-(ab-7)²=(ab)²-(ab-7)²=
=(ab+ab-7)(ab-ab+7)=7(2ab-7)=14ab-49
или :
a²b²-(ab-7)²=a²b²-(a²b²-14ab+49)=
=a²b²-a²b²+14ab-49=14ab-49