[tex]13)~24ab+30ac=6a(4b+5c)\\\\
14)~9x^3+9x^2y-x-y=9x^2(x+y)-(x+y)=(9x^2-1)(x+y)=\\\\=(3x-1)(3x+1)(x+y)\\\\
15)~x^3-10x^2+21x=x(x^2-10x+21)=(x-3)(x-7)\\\\
16)~6y^3-150y=6y(y^2-25)=6y(y-5)(y+5)\\\\
17)~8m^2+2m-3=(4m+3)(2m-1)\\\\
18)~2w^2+38w+140=2(w^2+17w+70)=2(w+7)(w+10)\\\\
19)~5x^3y-5xy=5xy(x^2-1)=5xy(x-1)(x+1)\\\\
20)~100-9y^2=(10-3y)(10+3y)[/tex]
