MCQ
Given $A=\left[\begin{array}{ccc}\sqrt{3} & 1 & -1 \\ 2 & 3 & 0\end{array}\right]$ and $B=\left[\begin{array}{ccc}2 & \sqrt{5} & 1 \\ -2 & 3 & \frac{1}{2}\end{array}\right],$ find $A+B$ $=$ ........
  • A
    $  \left[ {\begin{array}{*{20}{c}}
      {2 - \sqrt 3 }&{1 + \sqrt 5 }&0 \\ 
      0&6&{\frac{1}{2}} 
    \end{array}} \right]$
  • $  \left[ {\begin{array}{*{20}{c}}
      {2 + \sqrt 3 }&{1 + \sqrt 5 }&0 \\ 
      0&6&{\frac{1}{2}} 
    \end{array}} \right]$
  • C
    $  \left[ {\begin{array}{*{20}{c}}
      {2 + \sqrt 3 }&{1 - \sqrt 5 }&0 \\ 
      0&6&{\frac{1}{2}} 
    \end{array}} \right]$
  • D
    $  \left[ {\begin{array}{*{20}{c}}
      {2 + \sqrt 3 }&{1- \sqrt 5 }&0 \\ 
      0&6&{\frac{-1}{2}} 
    \end{array}} \right]$

Answer

Correct option: B.
$  \left[ {\begin{array}{*{20}{c}}
  {2 + \sqrt 3 }&{1 + \sqrt 5 }&0 \\ 
  0&6&{\frac{1}{2}} 
\end{array}} \right]$
b
since $A,\, B$ are of the same order $2 \times 3 .$ Therefore, addition of $A$ and $B$ is defined and is given by

$A + B = $ $\left[ {\begin{array}{*{20}{l}}
  {2 + \sqrt 3 }&{1 + \sqrt 5 }&{1 - 1} \\ 
  {2 - 2}&{3 + 3}&{0 + \frac{1}{2}} 
\end{array}} \right]$

$ = \left[ {\begin{array}{*{20}{c}}
  {2 + \sqrt 3 }&{1 + \sqrt 5 }&0 \\ 
  0&6&{\frac{1}{2}} 
\end{array}} \right]$

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