Expand and Simplify (5x - 2y)^2

We can rewrite this as (5x - 2y)(5x - 2y). Now all we have to do is expand the brackets. We can do this by multiplying all the terms in the second bracket by all the terms in the first bracket and then sum them all together. So we get (5x * 5x) + (5x * -2y) + (-2y * 5x) + (-2y * -2y) = 25x^2 - 10xy - 10xy + 4y^2 = 25x^2 - 20xy +4y^2