# Thread: help with calc what am i doing incorrectly

1. ## help with calc what am i doing incorrectly

Find all numbers c that satisfy the conclusion of the mean value theorem.
$f(x)=3x^2+2x+5, [-1,1]$

this is what i get
$f'(c)=\frac{f(b)-f(a)}{b-a}$
a=-1
b=1
so
$f'(c)=\frac{f(1)-f(-1)}{1-(-1)}$
= 2

never mind i figured it out
well tell me if this is correct
f'(c)=6c+2
6c+2=2
c=0

2. Looks good to me. Where were you tripping at first?