упростите вырожение (y-3)(y+5)-(y+1)^2

(y-3)(y+5)-(y+1)^2 = y^2 + 5y - 3y - 15 - (y^2 + 2y + 1) = y^2 + 5y - 3y - 15 - y^2 - 2y - 1 = 0.