Question

How do you multiply `(x-15y)(x+15y)`?

Answer 1

`x^2-225y^2`
This is a difference of squares where:
`(a^2-b^2) = (a+b)(a-b)`

If we let `a=x` and `b=15y`
`((x)^2-(15y)^2) = (x+15y)(x-15y)`