1. ## What's wrong with my answer? (Finding equations)

Given $f(x) = 3 - x - x^2$, find equation of $-f(x)$

The teacher didn't like my answer, what's wrong with the way I wrote this?

$f(x) = 3 - x - x^2$
$f(x) = -(3 - x - x^2)$
$f(x) = -3 - (-x) - (-x^2)$
$f(x) = -3 + x - x^2$

I don't know what I did wrong...

edit: I meant -f(x)

2. $f(x) = 3 - x - x^2$

$f(-x) = 3 - (-x) - (-x)^2 = 3+x-x^2$

3. Sorry, meant -f(x).

So what's wrong with the way I wrote it?

4. $
- f(x) = -(3 - x - x^2)
$

should be $-3 + x + x^2$