# Math Help - rearranging formula q

1. ## rearranging formula q

Hi everybody, can somebody tell me were I'm going wrong, this is driving me mad

Make p the subject

$\frac{{x}^{2 } }{{p}^{2 } } + \frac{{y}^{ 2} }{{q}^{ 2} }$ =1

I get

$\frac{x}{\sqrt[]{{q}^{2 }-{y}^{2 }}}$ =p

Which apparently is incorrect. I'd love to show you the steps I took, but this is my first ever post and I'm really struggling with the latex workaround.

2. Im wont try and diagnose your mistake without seeing your working. My attempt:

3. Hmmm, I get what you've done, but the answer the book gives is

$p=\frac{xq}{\sqrt[]{{q}^{2 }-{y}^{2 }}}$

4. Originally Posted by jharrisbr8
Hmmm, I get what you've done, but the answer the book gives is

$p=\frac{xq}{\sqrt[]{{q}^{2 }-{y}^{2 }}}$

$q > 0$
$p=\frac{x}{\sqrt{1-\frac{y^2}{q^2}}}=\frac{x}{\sqrt{\frac{q^2-y^2}{q^2}}} =\frac{x}{\frac{\sqrt{q^2-y^2}}{|q|}}=\frac{|q|x}{\sqrt{q^2-y^2}}$