implicit differentiation to find y' for 4x^2 + 9y^2 = 4

scrum

Junior Member
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Oct 11, 2007
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I'm having problems with implicit differentiation.

I have a problem

Find y' by implicit dfferentiation.

4x^2 + 9y^2 = 4

I differentiate to

8x + 18y * y' = 0

and solved to

y' = (-8x / 18y)

and this comes out as wrong :(

can someone tell me what I'm doing wrong.
 
4x^2+9y^2=4

differentiate both sides:

8x + 18yy' = 0

18yy' = -8x
y' = -8x/18y

looks good to me! Why do you think it is wrong?
 
It's a homework question that is making me submit them to a computer and it tells me whether or not the answer is correct.

It turns out i needed more (). it wanted ((-4x)/(9y)).
 
\(\displaystyle \frac{-8x}{18y} = \frac{2(-4x)}{2(9y)} = \frac{-4x}{9y}\)

They're identical. They just wanted the final answer with the coefficient as a reduced fraction.
 
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