Princess Poly has found most of the matches after spending a few hours working on the map of the garden and the labeled fences. She has one piece of fencing left and three rectangular plots it might belong to.

The polynomial label for the final section of fencing is r(x)=2x3+x2−41x+20.

One of the rectangular plots has a side labeled as c(x)=x+1.

Which method shows the correct way to test whether c(x) is a factor of r(x)?