`x^{2}+y^{2}-a^{2}-b^{2}-2xy+2ab`
`=(x^{2}-2xy+y^{2})-(a^{2}-2ab+b^{2})`
`=(x-y)^{2}-(a-b)^{2}`
`=[(x-y)+(a-b)].[(x-y)-(a-b)]`
`=(x-y+a-b)(x-y-a+b)`
x2+y2−a2−b2−2xy+2abx2+y2-a2-b2-2xy+2ab
=(x2−2xy+y2)−(a2−2ab+b2)=(x2-2xy+y2)-(a2-2ab+b2)
=(x−y)2−(a−b)2=(x-y)2-(a-b)2
=[(x−y)+(a−b)].[(x−y)−(a−b)]=[(x-y)+(a-b)].[(x-y)-(a-b)]
=(x−y+a−b)(x−y−a+b)