# Solving for y

1. Jun 17, 2011

### vanmaiden

solving for "y"

1. The problem statement, all variables and given/known data
Solve for y in 16y2 -24xy -300y +x2 + 400x = 0

2. Relevant equations
N/A

3. The attempt at a solution
16y2 -24xy -300y +x2 + 400x = 0
16y2 -24xy -300y = -x2 - 400x
y (16y - 24x - 300) = -x2 - 400x

When I get here, I can isolate the y but not the y

2. Jun 18, 2011

### Staff: Mentor

Re: solving for "y"

What you are calling y and y are the same thing, so you have not isolated y.

The equation is quadratic in y, so you can solve for y using the Quadratic Formula.
16y2 -24xy -300y +x2 + 400x = 0
<==> 16y2 + (-24x - 300)y + (x2 + 400x) = 0

This is now in the form ay2 + by + c = 0. Can you take it from here?

3. Jun 18, 2011

### hunt_mat

Re: solving for "y"

What mark44 is saying is that your equation is a quadratic in y, and there is a forumla for those.

4. Jun 18, 2011

### Mentallic

Re: solving for "y"

lol

5. Jun 18, 2011

### hunt_mat

Re: solving for "y"

Perhaps I should have read mark44's post a little more closely...

6. Jun 18, 2011

### vanmaiden

Re: solving for "y"

Thank you all for the help

I see what I should do now, but I continue to get weird answers when I plug it into the quadratic formula. I'm sure it's just too early for me to be doing this stuff lol. I'll continue trying.

Thank you

7. Jun 18, 2011

### Staff: Mentor

Re: solving for "y"

Not sure what you mean by "weird answers," but there will be two solutions for y, both involving x.