- #1

Sho Kano

- 372

- 3

## Homework Statement

Determine if the following is a subspace of ##P_3##.

All polynomials ##a_0+a_1x+a_2x^2+a_3x^3## for which ##a_0+a_1+a_2+a_3=0##

## Homework Equations

use closure of addition and scalar multiplication

## The Attempt at a Solution

Let ##P=a_0+a_1x+a_2x^2+a_3x^3## and ##Q=b_0+b_1x+b_2x^2+b_3x^3##

##P+Q=(a_0+b_0)+(a_1+b_1)x+(a_2+b_2)x^2+(a_3+b_3)x^3##

am I missing a step? how can I show that matches the conditions?