# Homework Help: Implicit differentiation question?

1. Apr 15, 2012

### shocklightnin

1. The problem statement, all variables and given/known data
use implicit differentiation to find an equation of the tangent line to the curve a the given point.

y^2(y^2-4) = x^2(x^2-5)

at (0,-2)

2. Relevant equations

y^2(y^2-4) = x^2(x^2-5)

3. The attempt at a solution

I got dy/dx to be (3x^2-10x)/(4y^3-8y)

but the answer book says otherwise:
(4x^3-10x)/(4y^3-8y)

while it works out with the point since 0/anything = 0 (which is the answer of what the slope it at that point) i ended up getting the wrong formula in the first place - how is one to do this question then?

2. Apr 15, 2012

### LCKurtz

So it is telling you exactly where your mistake is. What to you get when you differentiate the $x^4-5x^2$ on the right side?

3. Apr 15, 2012

### shocklightnin

good grief i had x^2(x-5) copied on my paper. goodness, nevermind haha. :