(y-4)(y+2)-(y-2)^2=-30
(y -4)(y+2) -(y -2)² = -30 y² -2y -8 -(y² -4y +4)= -30 y² -2y -8 -y² +4y -4 = -30 2y -12 = -30 2y = -30 +12 2y = -18 y = -18/2 y = -9