1. Factorisation with two variables

Does anyone have any ideas for the factors of this equation?
$4x^2-75xy-100y^2$

2. Hello,
Originally Posted by AShaw
Does anyone have any ideas for the factors of this equation?
$4x^2-75xy-100y^2$

Write (2x)²-75xy-(10y)²

Then, complete the square . (Completing the Square: Solving Quadratic Equations)

3. $(4x+5y)(x-20y)$

4. Originally Posted by AShaw
Does anyone have any ideas for the factors of this equation?
$4x^2-75xy-100y^2$

$=4x^2-75xy-100y^2$
$=4x^2-80xy+5xy-100y^2$
$=4x(x-20y)+5y(x-20y)$
$=(4x+5y)(x-20y)$