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Janellerhiannon
Dec 4, 2008, 09:08 PM
OK, so I'm familiar with implicit differentiation, but this problem is very difficult for me to solve.

Find (dy/dx) for the equation: y = x/(x+y)



PLEASE HELP!!

galactus
Dec 4, 2008, 10:25 PM
Do you know the quotient rule?

y=\frac{x}{x+y}

y'=\frac{(x+y)-xy'}{(x+y)^{2}}

Now, solve for y' and tidy up with some algebra.

Can you finish OK?

Janellerhiannon
Dec 7, 2008, 10:05 PM
Well, I got the quotient rule part down. It's just the algebra that I'm stuck on. I keep getting different answers.

mathkid
Feb 15, 2009, 04:13 PM
You should only get one answer.

If you are solving for dy/dx, try putting all of the dy/dx's on one side of the equation, and all Xs on the other side.

Combine like multiples and then solve for dy/dx.

:D