Exercise 46 Page 491

Remember, only like terms can be combined.

-4r^3+r-9

Practice makes perfect

The first step in simplifying this expression is to identify which, if any, terms can be combined. Remember, only like terms — constant terms or terms with the same variable and the same exponent — can be combined. ( -9r^3 + 2r - 1)-( -5r^3 + r + 8) In this case, we have two r^3-terms, two r-terms, and two constants. All terms can be combined, so to simplify the expression we will remove parentheses, rearrange it according to the Commutative Property of Addition, and then combine like terms.

(-9r^3+2r-1)-(-5r^3+r+8)

RemovePar

Remove parentheses

-9r^3+2r-1-(-5r^3+r+8)

Distr

Distribute -1

-9r^3+2r-1+5r^3-r-8

CommutativePropAdd

Commutative Property of Addition

-9r^3+5r^3+2r-r-1-8

AddSubTerms

Add and subtract terms