1) (а+b)^2-4ab=(a-b)^2
2) (a-b)^2+4ab=(a+b)^2
1)a2+2ab+b2-4ab=a2-2ab+b2
a2+2ab+b2-4ab-a2+2ab-b2=0
ответ:0
2)a2-2ab+b2+4ab=a2+2ab+b2
a2-2ab+b2+4ab-a2-2ab-b2=0