Posted by help on Thursday, July 5, 2012 at 8:25pm.
your simplification of the derivative is not correct
F ' (x) = 3x^2 + 6x - 9
now we set that equal to zero
3x^2 + 6x-9 = 0
divide each term by 3
x^2 + 2x - 3 = 0
which factors to
(x+3)(x-1) = 0
so x = -3 or x = 1
if x=1, f(1) = 1+3-9-13 = -18
if x=-3, f(-3) = -27 + 27 + 27 - 13 = 14
so the points are (1,-18) and (-3,14)
(I don't understand how you went from
if you expand 3x(x-3) you get 3x^2 - 9x , I don't see the 6x )
You should always check intermediate steps of your solution )
yes, you have the max or min. These are the localized extremes. Look at x=+- inf? what happens there? (But they are not local extremes. Read this example to see the difference between local extrema and global extrema.
I took out the 3x which gave me 3x(x+6-9) but if that's wrong...it's wrong :) thanks for the help!
Andddd I just realized to take out the 3 out the 6 and 9 T_T opps. Thanks, now I feel dumb XD
Algebra - Evaluate log36(1/6) I believe the answer is -.5 but I just wanted to ...
calculus - Jena. Stop it, or you will be banned. Using the chain rule, how do i ...
Math - I have to calculate the percent error for my experiment and I just wanted...
Chemistry - ok.. im confused: Ammonia and oxygen react in the equation: 4NH³...
calculus - graph the following function using transformations. Be sure to graph ...
math - hey everyone, i have a question, by looking at a particular graph, how ...
Just Curious - Hey. I was just wondering if anybody on here has been to teenink...
Calculus - Partial Integrals - I made this question, just wanted to make sure it...
science - I was just wondering! I posted a question for you all at 12:01 today. ...
calculus - The question I'm having problems with is If f(x)=3x^2+7x+2, find ...
For Further Reading