Question

Please help me !!!

Answer 1

3. 5mn ( 2m + 6n + 1 )
4. 4a^3b^2c ( 18a^2b - 8c )
5. (X-15)(X+15)
6. -4(y-4.5)(y+4.5)
8. 2X(X-10)(X+10)
i am not sure if no. 8 is right

Answer 2

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