разложите на множители
1)b^2c-9c
2) 2a^2+12a+18
3) 25a-ab^2
4) 3a^2-6a+3

=c(b²-9)=c(b+3)(b-3)=2(a²+2*3*a+9)=2(a+3)²=2(a+3)(a+3)=a(25-b²)=a(5-b)(5+b)=3(a²-2a+1)=3(a-1)²=3(a-1)(a-1)