2

I have followed the suggestions in this thread to place the delimiters before and After all arrays (also tried matrix} but my file won’t compile until I delinit each matrix which doesn’t give me the result I need.

  \documentclass[legalpaper,12pt]{amsart}
  \usepackage{amsmath,array}
   \begin{document}

  \[A =\begin{array}{r r r}
  2 & -1 & 0\\
  -1 & 2 & -1\\
  0 & -1 & 2
  \end{array}\]


  Describe the column space and the nullspace          of the matrices
  \[ A=\left(\begin{array}{c c}
   1 & -1\\
   0 & 0
  \end{array}\right)

  \qquad
  B=\begin{array}{c c c}
  0 & 0 & 3\\
  1 & 2 & 3
  \end{array}

  C=\begin{array}{c c c}
  0&0&0\\
  0&0&0

  \end{array}
  \]
  \end{document}

  • 4
    Don't put all-blank lines in display-math environment, including one delimited by \[ and \]. – Mico Oct 2 '19 at 21:02
3

Remove any blank lines inside math environments as @Mico said, and use pmatrix for all your matrices and \qquad between A, B, and C.

\documentclass[12pt]{amsart}
\usepackage{amsmath,array}

\begin{document}
  \[
  A =\begin{pmatrix}
    2 & -1 &  0 \\
   -1 &  2 & -1 \\
    0 & -1 &  2
  \end{pmatrix}
  \]
  Describe the column space and the nullspace of the matrices
  \[ 
   A = \begin{pmatrix}
   1 & -1 \\
   0 & 0
  \end{pmatrix}
  \qquad
  B = \begin{pmatrix}
  0 & 0 & 3\\
  1 & 2 & 3
  \end{pmatrix}
  \qquad
  C = \begin{pmatrix}
  0 & 0 & 0 \\
  0 & 0 & 0
  \end{pmatrix}
  \]
\end{document}

enter image description here

| improve this answer | |
2

Your basic problem is solved by @Mico comment, but you maybe looking for the following result:

enter image description here

\documentclass[legalpaper,12pt]{amsart}
\usepackage{mathtools}

\begin{document}
  \[
  A =\begin{pmatrix*}[r]
  2 & -1 & 0\\
  -1 & 2 & -1\\
  0 & -1 & 2
  \end{pmatrix*}
  \]
  Describe the column space and the nullspace of the matrices
  \[ 
  A=\begin{pmatrix*}[r]
   1 & -1\\
   0 & 0
  \end{pmatrix*}
  \qquad
  B=\begin{pmatrix}
  0 & 0 & 3\\
  1 & 2 & 3
  \end{pmatrix}
  \qquad
  C=\begin{pmatrix}
  0&0&0\\
  0&0&0
  \end{pmatrix}
  \]
\end{document}
| improve this answer | |
1

Same output can be obtained using spalign package with the attention to put a blank space between the elements of the matrix. The advantage of this package and to have directly the alignment the minus signs l, r, c. Here I have used the option r=right,\spalignmat[r].

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath}
\usepackage{spalign}
\begin{document}

\[ 
\spalignmat[r]{2 -1 0; -1 2 -1; 0 -1 2} 
\]
Describe the column space and the nullspace of the matrices:
\[A=\spalignmat[r]{1 -1; 0 0}, \quad B=\spalignmat[r]{0 0 3; 1 2 3}, \quad  C=\spalignmat[r]{0 0 0; 0 0 0}\]
\end{document}

enter image description here

| improve this answer | |

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