#### Answer

$f'(x)=1$
$f''(x)=0$
$f'''(x)=0$

#### Work Step by Step

Simplify the expression:
$f(x)=\dfrac{x^2-7x-8}{x+1}=\dfrac{(x+1)(x-8)}{x+1}=x-8$
Apply power rule to the function to find the first derivate:
$f'(x)=1$
Apply power rule to the first derivate to find the second derivate:
$f''(x)=0$
Apply power rule to the second derivate to find the third derivate:
$f'''(x)=0$