# Equation for y to obtain an equation that represents circle

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1. Feb 2, 2015

### Niaboc67

1. The problem statement, all variables and given/known data
The equation that is first listed is: 2x^2 + 2y^2 = 7

2. Relevant equations

3. The attempt at a solution

It's redefing the bottom portion therefore I think it's y=0,-2 because that is the range?

2. Feb 2, 2015

### phinds

I do not get how you think that is a solution. The solution is an equation in the form of y = f(x) such that it is represented by the graph shown (the lower portion of the circle. This is trivial.

3. Feb 2, 2015

### BvU

Is there something known about x that you forgot to tell us ?

4. Feb 2, 2015

### RUber

If you use some algebra to solve the circle equation for y, you should have a $\pm$ symbol in front of the x part. You want to either choose + or - based on what the plot shows.