4

I want to use the symbol for logical disjunction (the 'V'), but I want this to be in the center of the two 'x = ..'.

Right now it's like this:

enter image description here

This is the code I'm using:

\paragraph{a)}
$
\begin{aligned}[t]
&D=b^2-4ac=5^2-4\cdot-2\cdot3=49 \\
&x=\dfrac{-5+\sqrt{49}}{2\cdot-2}=-\dfrac{1}{2}
&\hfill 
&\vee 
&\hfill
&x=\dfrac{-5-\sqrt{49}}{2\cdot-2}=3
\end{aligned}
$
  • 1
    Please make your code compilable (if possible), or at least complete it with \documentclass{...}, the required \usepackage's, \begin{document}, and \end{document}. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to give you a hand. Help them help you: remove that one hurdle between you and a solution to your problem. – Thruston Nov 24 '14 at 18:59
  • 1
    Inside the environments of the amsmath package, the command \hfill doesn't work like it does in "ordinary" material. – Mico Nov 24 '14 at 19:00
  • I think this would be better handled by a gathered environment rather than an aligned... – Thruston Nov 24 '14 at 19:00
  • @Thruston The 'gathered' gives an error, I'm using documentclass{article} and I'm using the package 'amsmath' – user3024879 Nov 24 '14 at 19:03
2

Here is version using tabular or array (saves you having to go into and out of math mode for each cell) :

enter image description here

Notes:

  • The showframe package was used just to show the page margins. It is not needed in your actual use case.

Code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{array}
\usepackage{showframe}

\newcommand*{\Length}{\dimexpr0.45\linewidth-1.0em\relax}% Adjustment for the paragraph label.

\begin{document}
\paragraph{a)}
\begin{tabular}[t]{@{}p{\Length} @{}p{0.10\linewidth}<{\centering}@{} >{\hfill}p{\Length}@{}}
    $D=b^2-4ac=5^2-4\cdot-2\cdot3=49$ \\
    $x=\dfrac{-5+\sqrt{49}}{2\cdot-2}=-\dfrac{1}{2}$ & $\vee$  & $x=\dfrac{-5-\sqrt{49}}{2\cdot-2}=3$ \\
\end{tabular}
\paragraph{b)}
$\begin{array}[t]{@{}>{$}p{\Length}<{$} @{}>{\centering$}p{0.10\linewidth}<{$}@{} >{\hfill$}p{\Length}<{$}@{}}
    D=b^2-4ac=5^2-4\cdot-2\cdot3=49 \\
    x=\dfrac{-5+\sqrt{49}}{2\cdot-2}=-\dfrac{1}{2} & \vee  & x=\dfrac{-5-\sqrt{49}}{2\cdot-2}=3 \\
\end{array}$
\end{document}
2

For simple lists of equations like this all you really need is an array with a single column that you can align left, center, or right.

enter image description here

\documentclass{article}
\usepackage{amsmath}
\begin{document}

\paragraph{a)}
$
\begin{array}[t]{l}
D=b^2-4ac=5^2-4\cdot-2\cdot3=49 \\
x=\dfrac{-5+\sqrt{49}}{2\cdot-2}=-\dfrac{1}{2}
\qquad\text{or}\qquad 
x=\dfrac{-5-\sqrt{49}}{2\cdot-2}=3
\end{array}
$
\end{document}

Use \quad or \qquad to make space in a line, where there's no need to line things up.

  • Your code is like this:i.imgur.com/3ZOJbdO.png – user3024879 Nov 24 '14 at 19:40
  • But I want to have this: i.imgur.com/43p70Wa.png – user3024879 Nov 24 '14 at 19:41
  • can't you do it with the 'aligned'? – user3024879 Nov 24 '14 at 19:51
  • @user3024879 No not really - aligned is for lining things up on a specific character, usually the = sign. What you want is a simple array, with a single left-aligned column. – Thruston Nov 24 '14 at 23:12
0
\documentclass{article}
\usepackage{amsmath,showframe}
\begin{document}
\paragraph{a)}
$
\begin{aligned}[t]
&D=b²-4ac=5²-4\cdot-2\cdot3=49 \\
&x=\dfrac{-5+√{49}}{2\cdot-2}=-\dfrac{1}{2}
&
\vee
\qquad\qquad\qquad
&
&x=\dfrac{-5-√{49}}{2\cdot-2}=3
\end{aligned}
$
\end{document}

enter image description here

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