[tex]1)~28c-12=4(7c-3)\\\\
2)~x^2y+x=x(xy+1)\\\\
3)~10m^2n+30mn^2+5mn=5mn(2m+6n+1)\\\\
4)~72a^5b^3c-32a^3b^2c^2=8a^3b^2c(9a^2b-4c)\\\\
5)~x^2-225=(x-15)(x+15)\\\\
6)~81-4y^2=(9-2y)(9+2y)\\\\
7)~9k^4-25=(3k^2-5)(3k^2+5)\\\\
8)~2x^3-200x=2x(x^2-100)=2x(x-10)(x+10)\\\\
9)~72y^4-18y^2=18y^2(4y^2-1)=18y^2(2y-1)(2y+1)\\\\
10)~49x^3-xy^2=x(49x^2-y^2)=x(7x-y)(7x+y)[/tex]
