# Implicit diff.

1. Sep 3, 2008

### Jason03

Heres another problem I was working on....

http://img141.imageshack.us/img141/2318/calc2qg4.jpg

Im trying to find dy/dx using implicit differentiation.....my algebra is a bit rusty......but Im trying to make sure im on the right track....

2. Sep 3, 2008

### rocomath

Implicit diff of x^2 is not 2xy', it's just 2x. Everything else is fine.

3. Sep 3, 2008

### Jason03

where did I do that in the problem?

4. Sep 3, 2008

### Hitman2-2

Not quite;

When you are differentiating x2 with respect to x, for example, you simply get 2x. You do not multiply 2x by dy/dx.

However, when you (implicitly) differentiate y2 with respect to x (where y is a function of x) you get

$$2y \frac{dy}{dx}$$

Here you do multiply by dy/dx; the reason comes from the chain rule.

5. Sep 3, 2008

### Hitman2-2

Third line, first expression on the left hand side (referring to your attached image)

6. Sep 3, 2008

7. Sep 3, 2008

### Jason03

does the work above look ok?

8. Sep 3, 2008

### Hitman2-2

Looks fine to me