Question

FACTORISE:
25^2-70XY+49Y^2-64X^2
PLEASE ANSWER FAST
NO SPAM PLS

Answer 1

25x² + 70xy + 49y² = (5x + 7y)²

because :

a² + 2ab + b² = (a + b)²

Here we have :

a² = 25x² => a = 5x

and  

b² = 49y² => b = 7y

also

2ab = 2 * 5x * 7y = 2 * 5 * 7 * x * y = 70xy