Nastya1111111145 1)20с²-45=5(4с²-9)
2)7m²+14mn+7m²=7m(m+2n+m)=7m(2m+2n)
3)-3xy-24y-9x-72=(-3xy-24y)(-9x-72)=-3y(x-8)-9(x-8)=(x-8)(-3y-9)
4)a²-b²-b-a=(a-b)(a+b)+(a-b)=(a-b)(a+b)
5)x³-x²z+x²-xz=(x³+x²)(-x²z-xz)=x²(x+1)-xz(x+z)=(x+1)(x²-xz)