Question

18x^2 + 6 + 4x - 15x^2 - 4 + 13x
okay i know the answer is 3x^2 + 17x + 10 but i dont know how i got it can someone explain plz

Answer 1

put the terms in normal order:
18x^2 + 6 + 4x - 15x^2 - 4 + 13x
18x^2 - 15x^2 + 13x + 4x +6-4
now combine like terms
3x^2 +17x + 2

Unless you made a sign error, I dont agree with what you "know" is the answer.

Answer 2

18x^2 + 6 + 4x - 15x^2 - 4 + 13x

Combine like terms.

18x^2 - 15x^2 = 3x^2

6 - 4 = 2

4x + 13x = 17x