Compute $f'(x)$, $f''(x)$, $f'''(x)$, and then state a formula for $f^{(n)} (x)$, when

$f'(x)=$

$f''(x)=$

$f'''(x)=$

$f^{(n)}(x)=$

[Hint: The expression $(-1)^n$ has value $1$ if $n$ is even and $-1$ if $n$ is odd. This expression can be used in your answer for the last part.]