1. (y-4)*(y+4)-(y-3)^2
2.(b-4)*(b+2)-(b-1)^2
3.(a-2)*(a+4)-(a+1)^2
4.(a-c)*(a+c)-c*(3a-c)

1. y^2+4y-4y-16-(y^2-6y+9)=y^2+4y-4y-16-y^2+6y-9=-16+6-9=-192. b^2+2b-4b-8-(b^2-2b+1)=b^2+2b-4b-8-b^2+2b-1=-93.a^2+4a-2a-8-(a^2+2a+1)=a^2+4a-2a-8-a^2-2a-1=-94.a^2+ac-ac-c^2-3ac+c^2=a^2-3acвроде так