Help with calculus please?

Question

anonymous · Answer

If 2x2 + y2 = −2 then evaluate the second derivative of y with respect to x when x = 2 and y = 3.

anonymous · Answer

I'll fan or medal or whatever, just stuck on this one question.

anonymous · Answer

Do I find the second derivative, then plug in the values. Do I plug them in after differentiating once then differentiate again?

tkhunny · Answer

Did you find the first derivative?

anonymous · Answer

It's implicit derivative, so I'd find the derivative of both sides seperately, yeah? That'd be 2 y y'(x)+4 x = 0?

anonymous · Answer

Am I wrong? Can someone help further?

tkhunny · Answer

2x2 + y2 = −2

4x + 2yy' = 0

Agreed.  Now, the second derivative.  You need only one things you didn't use before, the product rule.  What are you going to do with 2yy'?

You can solve for y', first.  Sometimes that helps.  Sometimes, that just makes it worse.

anonymous · Answer

wait I think that was the wrong problem

-2x/y rather?

anonymous · Answer

Oh nvm

mathmale · Answer

Please double check.
Start over:  type in the problem you want to discuss.