x^2(a-b)+y(b-a)
=x^2(a-b)-y(a-b)
=(a-b)(x^2-y)
-49+36x^2y^2
=36x^2y^2-49
=(6xy-7)(6xy+7)
64(a-b)^2-25(a+b)^2
=[8(a-b)+5(a+b)][8(a-b)-5(a+b)]
=(8a-8b+5a+5b)(8a-8b-5a-5b)
=(13a-3b)(3a-13b)
-4xy-4x^2-y^2
=-(4x^2+4xy+y^2)
=-(2x+y)^2
9x^2-6x(y-8)+(y-8)^2
=[3x-(y-8)]^2
=(3x-y+8)^2
4x^2-4x(y-z)+(z-y)^2
=4x^2+4x(z-y)+(z-y)^2
=(2x+z-y)^2
5a^2b(x-y)^3-30ab^2(y-x)^2
=5a^2b(x-y)^3-30ab^2(x-y)^2
=5ab(x-y)^2[a(x-y)-6b]
=5ab(x-y)^2(ax-ay-6b)