Below a Question in Aviation SE I put a comment containing mathematical formulae. I had prepared the formulae using http://www.codecogs.com/latex/eqneditor.php. But it didn't become readable. Why? I paste below the results so you can understand:

I return on my second question. In order to have real solutions (\frac{T}{W}-G)^{2}-\frac{4*Cdo}{\pi ARe}\geq 0 . Then for simplicity of reasoning I define (\frac{T}{W}-G)=x and \frac{4*Cdo}{\pi ARe}=b . So the condition becomes x^{2}-b\geq 0 , but this (second grade) inequation is verified in both following zones: x\geq \sqrt{b} and also x\leq \left - \sqrt{b} \right i.e. \frac{T}{W}-G\geq 2\ast \ \sqrt{\frac{CD0}{\pi \ast AR\ast e}} and also \frac{T}{W}-G\leq-2\ast \ \sqrt{\frac{CD0}{\pi \ast AR\ast e}} . But Raymer exclude the second one, I don’t understand why.

  • Can you link to the post / comment? Aviation has mathjax enabled - did you delimit it correctly to make it identifiable as mathjax? – Oded May 17 '16 at 9:48
  • 2
    MathJax expressions should be delimited with $...$ (or $$...$$ for displayed equations). See, e.g., this fairly comprehensive guide from Mathematics. – user642796 May 17 '16 at 9:49
  • @Oded There seem to be a couple comments on this answer. – user642796 May 17 '16 at 9:50

But it didn't became something readable. Why?

Because you didn't enclose them with $$...$$ as required.

I have edited your comments on the answer to include those.

  • thank you very much Oded : it just have not be transformed $$ x\leq -\sqrt{b} $$ – d.pensopositivo May 17 '16 at 10:14
  • Yes, I noticed that, but I don't know why this has happened. The box around the equation shows it is recognized as mathjax, but it doesn't render it correctly. BTW - you will see that the comments have balooned - they are much too big now. – Oded May 17 '16 at 10:19
  • Also the previous my comment under the same question has ".... 1) Two different solutions ............ 2) Two coincident solutions : when....... 3) No solutions : when ..... ", but it happen that you put "2)" and "3)" inside the formulae and now I'm not allowed to edit it – d.pensopositivo May 17 '16 at 10:34
  • Just using single dollar-signs ($..$) would make the expressions inline, and cut down on the vertical space they take up. (Also, for the x \leq \left -\sqrt{b} \right expression, the \left and \right commands expect an extensible delimiter as an argument, which are absent. A relevant TeX - LaTeX question.) – user642796 May 17 '16 at 11:00
  • @arjafi - thanks for that, I didn't realize that delimiting $$ and $ would be so different. Updated comments. – Oded May 17 '16 at 11:05

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