Tuesday

March 31, 2015

March 31, 2015

Posted by **CharlieGolf** on Wednesday, June 20, 2007 at 7:02am.

Thank you very much. I did get the derivative you show, but then divided thru by 6 to get at the stationary points. Was that wrong?

I'm only looking for a critique please, not answers!

given: f(x)= −2x 3 +21x 2 − 60x+17

1. Is 1st deriv of this -x^2+7x-10 ?

2. stationary points x=2; x=5 ?

3. these are a local min and a local max?

Thanks

1. No. It is -6 x^2 +42 x-60.

2. See if the derivative is zero at both points. If so, the answer is yes.

3. Look at the second derivative. Evaluate it at x=2 and x=5. If the signs are + and -, the answer is yea. These cannot be absolute maxima and minima points because f(x) goes to + and - infinity.

Dividing by 6 is OK when setting the derivative equal to zero. When the derivative is zero, so is 1/6 the derivative. Note that 1/6 of the derivative is -(x-2)(x-5), so you can see right away where the stationary points are.

**Answer this Question**

**Related Questions**

Calc - ex: Find the indicated derivative using implicit differentiation. e^x/y^2...

science - Hi it's me again. I realize that my last question didn't make much ...

English - 1. I liked the work very much because I could help orphans who needed ...

Math - Calculus Question. - hey can someone explain to me the relationship ...

English - Hello. I'll be very grateful for some help again. Do you think it's OK...

music - what are singing points? As a music teacher, I've never heard of them. ...

Math - Given A=(1/2)(h)(a+b) Find: a. A if h=25, a=15, b=42 b. h if A=260, a=8, ...

to Ms.Sue & GuruBlue - Thank you so much for helping me out. I just don't ...

PLEASEEEEEEEEEEEEE HELP. (GEOMETRY) - A right triangle has hypotenuse 8 and area...

A thanks to Writeacher - THANK YOU lol thank you very much i now understand wat ...