Find the dimensions of the matrix $B = \left[ \begin{array} { c }
\frac { 2 } { 3 } \
3 \
0 \
- \frac { 4 } { 7 }
\end{array} \right]$
And identify the value of the element $b _ { 21 }$ .

A) $1 \times 4$ ; $b _ { 21 } = 3$
B) $4 \times 1$ ; $b _ { 21 } = 3$
C) $1 \times 4$ ; $b _ { 21 } = - \frac { 4 } { 7 }$
D) $4 \times 1$ ; $b _ { 21 } = 0$
E) $1 \times 4$ ; $b _ { 21 } = \frac { 2 } { 3 }$

Question

Find the dimensions of the matrix   $B = \left[ \begin{array} { c } 
\frac { 2 } { 3 } \
3 \
0 \
- \frac { 4 } { 7 }
\end{array} \right]$  
And identify the value of the element $b _ { 21 }$ .
 
A) $1 \times 4$ ; $b _ { 21 } = 3$
B) $4 \times 1$ ; $b _ { 21 } = 3$
C) $1 \times 4$ ; $b _ { 21 } = - \frac { 4 } { 7 }$
D) $4 \times 1$ ; $b _ { 21 } = 0$
E) $1 \times 4$ ; $b _ { 21 } = \frac { 2 } { 3 }$

Quizplus · Accepted Answer

The matrix B is a column matrix with 4 rows and 1 column, hence its dimensions are $4 \times 1$. The element $b_{21}$ refers to the second row, first column, which is $3$.

Find the Dimensions of the Matrix B=[2330−47]B = \left[ \begin{array} { c } \frac { 2 } { 3 } \\3 \\0 \\- \frac { 4 } { 7 }\end{array} \right]B=​32​30−74​​​

Find the Dimensions of the Matrix $B = \left[ \begin{array} { c } \frac { 2 } { 3 } \\3 \\0 \\- \frac { 4 } { 7 }\end{array} \right]$