Question

25 x square - 70 X Y + 49 y square

Answer 1

$25 {x}^{2} - 70xy + 49 {y}^{2} \\ \\ = > {(5x)}^{2} - 2(5x)(7y) + {(7y)}^{2} \\ \\ As \: we \: know \: that: \: {(a - b)}^{2} = {a}^{2} - 2ab + {b}^{2} \\ \\ Here, \: a = 5x \: and \: b = 7y \\ \\ = > {(5x - 7y)}^{2}$

Answer 2

as formula we know ( a-b)^2= a^2+ab-b^2
therefore ,
(5x-7y)^2=(5x)^2+7y^2-2*5x*7y
= 25 X square + 49 y square-2*5*7x
hence ur ans is (5x-7y)^2