# Thread: prove using simultaneous equation?

1. ## prove using simultaneous equation?

Having trouble with a prove, I'm not sure where to put this question.

2. ## Re: prove using simultaneous equation?

y = b/2x
Substitute it in the first equation and simplify. Then solve the quadratics to get x^2.

3. ## Re: prove using simultaneous equation?

Originally Posted by sa-ri-ga-ma
y = b/2x
Substitute it in the first equation and simplify. Then solve the quadratics to get x^2.
hi, thanks. I got that part, I'm just not sure how to simplify it.

4. ## Re: prove using simultaneous equation?

x^2 - (b / (2x))^2 - a = 0

4x^4 - 4ax^2 - b^2 = 0

Let u = x^2

4u^2 - 4au - b^2 = 0

Can you finish it?

5. ## Re: prove using simultaneous equation?

Originally Posted by Wilmer
x^2 - (b / (2x))^2 - a = 0

4x^4 - 4ax^2 - b^2 = 0

Let u = x^2

4u^2 - 4au - b^2 = 0

Can you finish it?
thanks, I think I still am having a bit of trouble with it. Do I have to complete the square or?

6. ## Re: prove using simultaneous equation?

Originally Posted by chessweicong
thanks, I think I still am having a bit of trouble with it. Do I have to complete the square or?