You can
put this solution on YOUR website!
Factor completely: (x+3y)^2-(2x+5y)^2
This is a speacial case: the difference of two squares
x^2 - y^2 = (x - y) (x + y)
(x+3y)^2-(2x+5y)^2 = [(x+3y)-(2x+5y)][(x+3y) + (2x+5y)]
= [(x+3y)-1(2x+5y)][(x+3y) + (2x+5y)]
= (x + 3y - 2x - 5y)(x + 3y + 2x +5y)
= (-x - 2y)(3x +8y)