Factorise: 9−a2+2ab−b2
9−a2+2ab−b2=9−(a2−2ab+b2)=32−(a−b)2=[3−(a−b)][3+(a−b)]=(3−a+b)(3+a−b)
How can we factorise a2 + 2ab + b2 -9
Factorise: 25−a2−b2−2ab