(3x – 4y) (3x + 4y) = By Admin ReiPosted on December 4, 2022 (3x – 4y) (3x + 4y) = (3x+4y)(3x+4y)=9x²+12xy+12xy+16y²=9x²+24xy+16y² (a-b) (a+) = a²-b = 3x²-4y