Question

If A=[1,2,3] then the set of the elements of \[A\] is
A \[\left\{ {1,2,3} \right\}\]
B \[\left\{ {2,0} \right\}\]
C only 2
D None of the above

Answer 1

Hint: Now here we are given in the question \[A = \left[ {123} \right]\] which represents a matrix and we are asked to find the elements of \[A\]. So to approach these kind of the question we need to keep in mind the representation of a certain how it is done and how does it give the indication about its elements so let us see the correct answer of the given question in the complete step by step solution

Complete step-by-step answer:
Here we are given in the question \[A = \left[ {123} \right]\] and we are asked the set of the elements of \[A\]
So first of all we should know how a matrix is represented
 \[\left( {\begin{array}{*{20}{c}}
  a&b \\
  c&d
\end{array}} \right)\] so it is a matrix of the order \[2*2\] that is it has two rows and two columns and it is a square matrix of the order \[2*2\] (a square matrix is a type of matrix in which both rows and columns are equal) with the elements of the matrix being the \[a,b,c,d\] and can be written as \[\left[ {abcd} \right]\]
Now here in the question we are given \[A = \left[ {123} \right]\] and we are asked to find the elements of \[A\] that implies the matrix \[A\] is given to us with the elements \[\left\{ {1,2,3} \right\}\] according to the facts as we have seen above about the matrix and its elements so the elements of the \[A = \left[ {123} \right]\] is equal to \[\left\{ {1,2,3} \right\}\]and the option that is same as our solution is A \[\left\{ {1,2,3} \right\}\].
Hence the correct option is A.

Note: While solving such kind of questions one should have a basics clear about the matrices and its representation and the terms related to it also some other variety of the matrices like square matrix (as stated above it is a matrix having same number of rows and columns ). Also the identity matrix it is a type of the matrix in which the all the elements of the principal diagonal is \[1\] that is
\[\left( {\begin{array}{*{20}{c}}
  1&0 \\
  0&1
\end{array}} \right)\] it is an example of an identity matrix and it is represented as \[{I_n} = \left[ 1 \right]\]where n is the order of the matrix.