(13x2 + 5x) + 8x2 =
(13x² + 5x) + 8x²= (13 + 8)x² + 5x= 21x² + 5x
Good evening
(13x² + 5x) + 8x²
First you need to eliminate the parentheses
13x² + 5x + 8x²
Now group the common terms
13x² + 8x² + 5x
21x² + 5x
I hope that's help:)