Question

simplify the following (2x+3y)(2x-3y)

Answer 1

= $(2x)^{2}$ - $(3y)^{2}$
 = $4 x^{2}$ - $9 y^{2}$

Answer 2

2x(2x-3y)+3y(2x-3y)=4x^2-6xy+6xy-9y^2