SOLUTION: The question asks "Which of the following must be even?" and it lists 5 answer choices in function notation. How do I go about identifying which equations are even? 1. x^2+6x+9

Algebra ->  Functions -> SOLUTION: The question asks "Which of the following must be even?" and it lists 5 answer choices in function notation. How do I go about identifying which equations are even? 1. x^2+6x+9       Log On


   

Question 1078074: The question asks "Which of the following must be even?" and it lists 5 answer choices in function notation. How do I go about identifying which equations are even?
1. x^2+6x+9
2. x^2+7x+12
3. x^2+4x-21
4. x^2+4x-12
5. x^2+8x+15
Thanks for your help!
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
For an even function, f%28x%29=f%28-x%29
For example, for number 1,
x%5E2%2B6x%2B9=%28-x%29%5E2-6x%2B9
x%5E2%2B6x%2B9=x%5E2-6x%2B9
12x=0
x=0
No, this is only valid when x=0 so it is not even.
Do the same for the remaining 4 choices.