Originally Posted by

**driver327** I have to use the Mean Value Theorem to find f'(c)

1. x^3+x on [1,2] the answer says c=1.52775...

2. x^4+2 on[-1,2] the answer says c=1.0772...

For 1, I found the deriv. which is 3x^2+1 , applied 1 and 2 to the original equation and got 4 and 13 respectively. plugged them into the MVT equation:

13-4/2-1=9. I plugged the 9 with the derivitive 3x^2+1 for it to become 3x^2+1-9=3x^2-8. make x stand by itself and got x= +or-(sqrt 8/3). and it doesn't add up to the answer.

For 2, Long story short, I did the exact same steps as in #1 and the result was the same.