Question

Use the expression (8x + 2) + (-9x + 7).

a. Find the sum.
b. Reasoning Explain how you know when to combine terms with variables.

Answer 1

-x + 9

Explanation:

Addition of expression:

a)

8x + 2 + (-9x + 7) = 8x + 2 - 9x + 7

= 8x - 9x + 2 + 7

= -x + 9

b) We can combine like terms. Like terms have same variable with same power. Here 8x and (-9x) have same variable 'x'. so, combine the coefficients of the like terms which give (-1).

8x - 9x = -1

Combine the constants. 2 + 7= 9