`a,` `(2x+1)^2+2(2x+1)+1 = (2x+1+1)^2 = (2x+2)^2`
`b,` `(3x-2y)^2+4(3x-2y)+4 = (3x-2y+2)^2`
`c,` `(2x+1)^2 = (2x)^2 + 2*2x*1 + 1^2 = 4x^2 + 4x + 1`
`d,` `(x^2+2)^2 = (x^2)^2 + 2*x^2*2 + 2^2 = x^4 + 4x^2 + 4`
`e,` `(2x+3y)^2 = (2x)^2 + 2*2x*3y + (3y)^2 = 4x^2 + 12xy + 9y^2`
`f,` `(x-3)(x+3) = x^2 - 3^2 = x^2 - 9`