hi i am beginner in latex and i am trying to write these 2 equations however i got different errors what is wrong with this code ? please,can anyone help ? thanks in advance


$Support(X  )= \frac{No,of\; transactions\;  that \; contain\;  X}{No,of \;transactions\; in\; the \;database}$



$confidence(X \longrightarrow Y)$=$ \frac {Support (X \cup Y) }{ support(X)}$

The error messages are:

Missing $ inserted. 
Display math should end with $$.
Bad math environment delimiter. \end{equation} 
  Missing $ inserted. \end{equation}
  You can't use `\eqno' in vertical mode. 
  • 4
    (1) welcome, (2) \begin{equation}...\end{equation} is already math mode, so no $...$ in there, (3) blank lines are not allowed inside math envs
    – daleif
    Jun 30, 2017 at 9:56
  • (1)thank you for answering(2) i deleted the blank lines but i still have the same errors messages
    –  DrCh
    Jun 30, 2017 at 10:02

1 Answer 1


I think the following may be what you're looking to write. Observe the use of \text in the numerator and denominator of the first equation. I encased the term X in the first numerator in $ symbols to inform LaTeX that it (the X) should be processed in math mode.

Observe also that there must be no blank lines in a display-math environment (such as equation).

enter image description here


\usepackage{amsmath} % for "\text" and "\DeclareMathOperator" macros


\Support(X) = \frac{\text{No of transactions that contain $X$}}%
                   {\text{No of transactions in the database}}

\Confidence(X \longrightarrow Y) = \frac{\Support(X\cup Y)}{\Support(X)}

  • thank you it works i will make sure to use \text in the next times
    –  DrCh
    Jun 30, 2017 at 10:19

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