<span>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</span>
Буду писать сразу ответ без примера
1) a²-2ab-(9b²+6ab+a²)=a²-2ab-9b²-6ab-a²=-8ab-9b²
2) m²+16m+64-(m²-4n²)=m²+16m+64-m²+4n²=16m+64+4n²
3) 3(b²-20b+100)+8b-5b²=3b²-60b+300+8b-5b²=-2b²-52b+300
4) n²+30n+225-n²+19n=49n+225
5) 36b²-12c-(36c²+12c+1)=36c²-12c-36c²-12c-1=-24c-1
6) (6-5m)×(6+5m)+25m²-40m+16=36-25m²+25m²-40m+16=52-40m
Решение задания приложено