# Math Help - How do I iso late x in the following eqation:

1. ## How do I iso late x in the following eqation:

Lr = Hx -Lx -r²x -rx²

In other words how do I define x in terms of the other units: x =

Thanks.

2. $\displaystyle L\,r = H\,x - L\,x - r^2x - r\,x^2$

$\displaystyle L\,r = -r\,x^2 + (H - L - r^2)x$

$\displaystyle -L = x^2 + \left(\frac{L + r^2 - H}{r}\right)x$.

Now complete the square.

3. x^2 + Kx + L = 0 where K = (L + r^2 - H) / r

x = [-K +- sqrt(K^2 - L^2)] / 2

Isn't that good nuff?

4. ## Thanks

Thanks to both of you. I have forgotten all my school algebra but I will try completing the square and will get back to you if I get stuck. I am 70 and my brain doesn't work like it use to.

Baz