how to use \left and \right in latex

Question

\[  
\begin{aligned}
 \left{x= [1,0]^{T}t \right) \Rightarrow x^{T}Ax = \alpha > 0,t \\ 
 x= [1,0]^{T} \Rightarrow x^{T}Ax = \gamma > 0),\\
 x = [1,1]^{T} \Rightarrow x^{T}Ax = \alpha  + 2\beta + \gamma  > 0,\\
 x = [1,-1]^{T}  \Rightarrow x^{T}Ax = \alpha - 2\beta + \gamma  > 0.
 \end{aligned} 
 \right\]

i want to use left and right in my code and i he dont accept with textstudio

did you intend \left( ? but there is no need for left or right there, I would just use (x= [1,0]^{T}t ) but do you really want parenthesis around the equation term? — David Carlisle, Jan 22 '20 at 18:46
i have try this but something done wrong he did not accepted — constantinos georgiou, Jan 22 '20 at 18:47
if you want help with an error show a complete small document that makes the error so people can run it and see the problem. — David Carlisle, Jan 22 '20 at 18:48
Does this answer your question? What do the pieces of LaTeX, \left and \right, respectively mean? — Vincent, Jan 22 '20 at 18:54
If you want scaled left and right curly braces, you need to use \{ and \}. Just { and } will be interpreted as opening and closing a group. — Davislor, Jan 22 '20 at 20:39

Zarko · Accepted Answer · 2020-01-23T02:46:13.067

Like this?

\documentclass{article}
\usepackage{mathtools}    % <--- for advanced math

\begin{document}
    \[\setlength\arraycolsep{1pt}
\begin{Bmatrix*}[l]      % defined in "mathtools"
x & = [1,0]^{T}t  \Rightarrow x^{T}Ax = \alpha > 0,t \\
x & = [1,0]^{T}   \Rightarrow x^{T}Ax = \gamma > 0),\\
x & = [1,1]^{T}   \Rightarrow x^{T}Ax = \alpha  + 2\beta + \gamma  > 0,\\
x & = [1,-1]^{T}  \Rightarrow x^{T}Ax = \alpha - 2\beta + \gamma  > 0.
 \end{Bmatrix*}
    \]
\end{document}

The package mathtools (which also load amsmath package) improved amsmath with some new features as is {...matrix*}[<align>] where you can determine how the matrix cells are aligned (in your case at left). Letter in place of ... define type of matrix delimiters. For details see some introductory text about typesetting math in LaTeX (for example wiki: advanced math).

Note: Please, always in question provide MWE (Minimal Working Example) complete small document, which we can test as it is. It is not fun to write such document from scratch knowing, that it already exist at you ...

Addedendum: You may like the following layout of your system of equations:

\documentclass{article}
\usepackage{mathtools}    % <--- for advanced math

\begin{document}
    \[\setlength\arraycolsep{1pt}
\begin{Bmatrix*}[l]      % defined in "mathtools"
x & = [1,0]^{T}t  & \Rightarrow x^{T}Ax = \alpha > 0,t \\
x & = [1,0]^{T}   & \Rightarrow x^{T}Ax = \gamma > 0),\\
x & = [1,1]^{T}   & \Rightarrow x^{T}Ax = \alpha  + 2\beta + \gamma  > 0,\\
x & = [1,-1]^{T}  & \Rightarrow x^{T}Ax = \alpha - 2\beta + \gamma  > 0.
 \end{Bmatrix*}
    \]
\end{document}

Of course, the similar result you can obtain for example with

\[\setlength\arraycolsep{1pt}
\left\{\begin{array}{ll}
x & = [1,0]^{T}t  \Rightarrow x^{T}Ax = \alpha > 0,t \\
x & = [1,0]^{T}   \Rightarrow x^{T}Ax = \gamma > 0),\\
x & = [1,1]^{T}   \Rightarrow x^{T}Ax = \alpha  + 2\beta + \gamma  > 0,\\
x & = [1,-1]^{T}  \Rightarrow x^{T}Ax = \alpha - 2\beta + \gamma  > 0.
     \end{array}\right\}
\]

or

\[
\left\{\begin{aligned}
x & = [1,0]^{T}t  \Rightarrow x^{T}Ax = \alpha > 0,t \\
x & = [1,0]^{T}   \Rightarrow x^{T}Ax = \gamma > 0),\\
x & = [1,1]^{T}   \Rightarrow x^{T}Ax = \alpha  + 2\beta + \gamma  > 0,\\
x & = [1,-1]^{T}  \Rightarrow x^{T}Ax = \alpha - 2\beta + \gamma  > 0.
     \end{aligned}\right\}
\]

etc

how to use \left and \right in latex

1 Answers1