Question

(y-1)(y+2)+(y+1)(y-2)​

Answer 1

$(y - 1)(y + 2) + (y + 1)(y - 2) = y {}^{2} + 2y - y - 2 + y {}^{2} - 2y + y - 2 = y { }^{2} + y {}^{2} - 4 = 2y {}^{2} - 4$