I have the calculator portion of my Ch. 3 Calculus test tomorrow, titled Derivatives.

I'm doing a review sheet right now, and am stuck on a problem.

If f(x) = 13 - 8x + √2x² + 1

and f '(r) = 4

find r.

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- Oct 8th 2008, 01:47 PMJBknights10Derivatives Problem
I have the calculator portion of my Ch. 3 Calculus test tomorrow, titled Derivatives.

I'm doing a review sheet right now, and am stuck on a problem.

If f(x) = 13 - 8x + √2x² + 1

and f '(r) = 4

find r. - Oct 8th 2008, 02:42 PM11rdc11
Just take the derivative of your 1st function and set it equal to 4 and replace x with r. Solve for r.

- Oct 8th 2008, 03:20 PMJBknights10
I think I messed up taking the derivative of √2x² because f ' (x) came out to be like -6

What is the derivative of √2x² is it just 2? - Oct 8th 2008, 03:42 PMmr fantastic
- Oct 8th 2008, 04:01 PMJBknights10
- Oct 8th 2008, 07:29 PMmr fantastic