## Introductory Algebra for College Students (7th Edition)

-11$r^{4}$ + r
(7$r^{4}$+5$r^{2}$ + 2r) + (-18$r^{4}$ -5 $r^{2}$ -r) The like terms are 7$r^{4}$ and -18$r^{4}$ (both containing $r^{4}$) , 5$r^{2}$ and -5 $r^{2}$ (both containing $r^{2}$) , 2r and -r (both containing r). We begin by grouping these pairs of like terms =(7$r^{4}$ -18$r^{4}$) + (5$r^{2}$ - 5 $r^{2}$) + ( 2r - r) = -11$r^{4}$ + r