...is

My book says the second derivative of a circle is also

Every time I do it, I get

So what is the 2nd derivative of a circle?

Por favor show some steps or tell me how you did it?

Ty

Edit:oops! wrong secition. This isn't homework.

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- Dec 12th 2007, 05:04 PMTruthbetoldSlope of a Circle
...is

My book says the second derivative of a circle is also

Every time I do it, I get

So what is the 2nd derivative of a circle?

Por favor show some steps or tell me how you did it?

Ty

Edit:oops! wrong secition. This isn't homework. - Dec 12th 2007, 06:16 PMKrizalid
- Dec 12th 2007, 06:30 PMTruthbetold
Got it solved by help from somewhere else.

The book doesn't say y''= -x/y

It doesn't say anything about the derivative of -x/y, even thouhg they ask you to do it and its an odd problem. Very strange this book.

y'' solved by complicated methods i've never heard before = - Dec 12th 2007, 09:32 PMearboth
Hi, obviously you are refering to a circle with the equation

Then the first derivative (using implicite derivation) is

To get the second derivative use quotient rule and chain rule:

Substitute y':

Use the first equation and you'll get:

Actually you have to consider 2 cases:

1. The conditions of the upper hemisphere

2. The conditions of the lower hemisphere