\(x^3+2x^2y+xy^2-25x\)
\(=x\left(x^2+2xy+y^2-25\right)\)
\(=x\left[\left(x+y\right)^2-5^2\right]\)
\(=x\left(x+y-5\right)\left(x+y+5\right)\)
= ( x3 + 2x2y + xy2 ) - 25x
= x.(x2 + 2xy + y2 ) - 5x2
= x.( x + y )2 - 5x2
= x. [(x + y) + 5x]. [( x + y) - 5x]