Question

calcule o produto (y-4). (y+4)

Answer 1

(y-4).(y+4)
y^2 +4y-4y-16
y^2-16

Answer 2

$(y-4)\cdot (y+4)\\ \\ =y\cdot (y+4)-4\cdot (y+4)\\ \\ =y^{2}+4y-4y-16\\ \\ =y^{2}-16$