[tex]17)~(x^2-x+3)(4x+1)=4x^3+x^2-4x^2-x+12x+3=\\\\=4x^3-3x^2+11x+3\\\\
18)~x(x+2)-3\cdot7=x^2+2x-21\\\\
19)~54x^3y-18x^2y^2+27xy^2=9xy(6x^2-2xy+3y)\\\\
20)~9x^2-49y^2=(3x-7y)(3x+7y)\\\\
21)~64y^4-16y^6=16y^4(4-y^2)=16y^4(2-y)(2+y)\\\\
22)~n^3-5n^2-50n=n(n^2-5n-50)=n(n+5)(n-10)\\\\
23)~4x^3+12x^2-25x-75=4x^2(x+3)-25(x+3)=\\\\=(4x^2-25)(x+3)=(2x-5)(2x+5)(x+3)\\\\
24)~3x^2-57x+180=3(x^2-19x+60)=3(x-4)(x-15)[/tex]
