Выражение 1) (9a-2)(9а+2)-18a 2)25m^{2}-(5m-7)(5m+7) 3)(b+7)(b-4)+(2-6)(2b+6) 4)4x(3x-+y)(4x-y)

1) (9a-2)(9а+2)-18a=81a²-4-18a
2)25m^{2}-(5m-7)(5m+7)=25m²-25m²+49=49
3)(b+7)(b-4)+(2-6)(2b+6)=b²-4b+7b-28-4b²+36=-3b²+3b+8
4)4x(3x-10y)-(4x+y)(4x-y) =12x²-40xy-16x²+y²=-4x²-40xy+y²