Chapter 10 Counting Methods and Probability - 10.2 Use Combinations and Binomial Theorem - 10.2 Exercises - Skill Practice - Page 695: 20

$$x^6+18x^5+135x^4+540x^3+1215x^2+1458x+729$$

We know from the Binomial Theorem (page 693) that we can expand the given expression using Pascal's Triangle. Doing this, we obtain: $$x^6+18x^5+135x^4+540x^3+1215x^2+1458x+729$$