# Homework Help: Implicit Differentiatoin question

1. Sep 26, 2005

### compute_a_nerd

Hello all.
I am given the equation $$(x^3 y^4)^5 = x-y$$

my derivative is $$1/ (15x^2 20y^3(x^3y^4)^4)=y'$$

But the book says: $$y'=(1-15x^14y^20)/(1+20x^15y^19)$$

Where did I go wrong?

Thanks so much
Chris

2. Sep 26, 2005

### Tide

You didn't differentiate the left side correctly. Try again.

3. Sep 27, 2005

### Fermat

You need to put curly brackets around all of your power if there is more than one character involved - like so,

$$y'=(1-15x^{14}y^{20})/(1+20x^{15}y^{19})$$

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