ok first thing your gonna want to do there is factor out the gcf, the greatest common factor, which in this case, is 3, you then get 3(7k^3-28k^2+5k-20). you then want to ignore your 3 and group some of your terms together so if you group them together you can take (7k^3 - 28k^2) and (5k-20) you then gcf those so you get 7k^2( k - 4) and 5(k-4) you notice that both have k-4? they should always both have the same thing inside the parentheses like that. now you take (7k^2+5)(k-4) this will sometimes be your ending point, but we cant forget aobut the gcf in the beginning. your final answer is 3(7k^2+5)(k-4)
