Factorize:
4(x−y)2+12(x−y)(x+y)+9(x+y)2
=[2(x−y)]2+2×2(x−y)×3(x+y)+[3(x+y)]2
[Using the identity,a2+2×a×b+b2=(a+b)2]
Here, a=2(x−y), b=3(x+y)
=[2(x−y)+3(x+y)]2
=(2x−2y+3x+3y)2
=(5x+y)2
12(x+y)2−(x+y)−35