### Home > A2C > Chapter 9 > Lesson 9.3.2 > Problem 9-140

9-140.

Carlo was trying to factor the polynomial

*p*(*x*) =*x*^{4}− 4*x*^{3}− 4*x*^{2}+ 24*x*− 9 and find all of its roots. He had already found one factor by making a guess and trying it, so he had*p*(*x*) = (*x*− 3)(*x*^{3}−*x*^{2}− 7*x*+ 3). He was trying to factor*x*^{3}−*x*^{2}− 7*x*+ 3, and he had tried (*x*+ 3), (*x*+ 1), and (*x*− 1), but none worked. Then Teo came by and said, “*You should look at the graph*.” Homework Help ✎How does the graph help?

Complete the problem.

It shows us that 3 is a double root which means (*x* − 3)^{2} is a factor.

Divide *x*^{3} − *x*^{2} − 7*x* + 3 by *x* − 3.

Use a multiplication rectangle to set it up.

Now use the quadratic formula to solve for *x*.