1) (2x-3)^2 = (2x-3)(2x-3)
= (2x)(2x) + (2x)(-3) + (-3)(2x) + (-3)(-3)
= 4x^2 - 6x - 6x + 9
= 4x^2 - 12x + 9

2) (3-4y)^2 = (3-4y)(3-4y)
= (3)(3) + (3)(-4y) + (-4y)(3) + (-4y)(-4y)
= 9 - 12y - 12y + 16y^2
= 9 - 24y + 16y^2