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Model Paper 3 — MATHS STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSModel Paper 31 Mark
Question
Conisder the matrices
$A=\left[\begin{array}{rrr} 2 & 1 & 3 \\ 3 & -2 & 1 \\ -1 & 0 & 1 \end{array}\right], B=\left[\begin{array}{rr} 1 & -2 \\ 2 & 1 \\ 4 & 3 \end{array}\right], C=\left[\begin{array}{lll} 1 & 2 & 6 \end{array}\right] $
Then, which of the following is not defined?
✓

Answer

(a) BA
Explanation: The given matrices are
$A=\left[\begin{array}{rrr}2 & 1 & 3 \\3 & -2 & 1 \\-1 & 0 & 1\end{array}\right], B=\left[\begin{array}{rr}1 & -2 \\2 & 1 \\4 & 3\end{array}\right] \text {, and } C=\left[\begin{array}{lll}1 & 2 & 6\end{array}\right]$
The order of $A$ is $3 \times 3$, order of $B$ is $3 \times 2$ and order of $C$ is $1 \times 3$.
$\therefore CA , AB$ and CB are all defined.
But BA is not defined as number of columns in B is not equal to the number of rows in A .

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