Упростите выражение 1)(a+b)^2-(a-b)^2 2)(m+4)^2-4(m+1)^2
3)3(2-y)^2+4(y-5)
4)5(3-5x)^2-5(3x-7)(3x+7)
5)(a+1)^2+3(a-1)^2-5(a-1)(a+1)
6)(x-1)^2-4(x+1)^2-6(x+1)(x-1)

1) (a+b)^2-(a-b)^2=a^2+2ab-b^2-(a^2-2ab+b^2)=a^2+2ab+b^2-a^2+2ab-b^2=a^2-a^2+2ab+2ab+b^2-b^2=0+4ab+0=4ab