I have the following equation:

E(W) = \frac{\frac{(c\rho)^c}{c!}}{(1-\rho)\sum_{n=0}^{c-1}(\frac{(c\rho)^n}{n!})+\frac{(c\rho)^c}{c!}} \cdot \frac{1}{1-\rho} \cdot \frac{1}{c\mu}

which is rendered as


Is there any easy way to prevent that the nominator and denominator of the main fraction to be each displayed in inline math mode? E.g. I want my summation to look like this enter image description here instead of the way it looks right now.

  • 2
    You can use \displaymath for example.
    – Sebastiano
    Nov 30, 2020 at 21:11
  • but as far as I understand this the equation is already in display math, or is there a way to force display math for the individual elements of the equation aswell?
    – charelf
    Nov 30, 2020 at 21:12
  • 2
    add \limits directly after the \sum command \sum\limits_{n=0}^{c-1} ...
    – Alan Munn
    Nov 30, 2020 at 21:15
  • 5
    Sebastiano meant \frac{\displaymath ...}{\displaymath ...} so numerator and denominator are set in display style Nov 30, 2020 at 21:16
  • 1
    Thanks all of you this has helped me!
    – charelf
    Nov 30, 2020 at 21:24

1 Answer 1


Here there is my version using also \displaystyle and \dfrac. I not very good for the explanations :-).

enter image description here


E(W) = \frac{\dfrac{(c\rho)^c}{c!}}{(1-\rho)\displaystyle\sum_{n=0}^{c-1}\left(\frac{(c\rho)^n}{n!}\right)+\frac{(c\rho)^c}{c!}} \cdot \frac{1}{1-\rho} \cdot \frac{1}{c\mu}

However you can see also this link: equal size numerator and denominator

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