Question Bank - Mathematics

Here's the question bank on all the mathematics topics.

Consider the following in respect of the matrices:\(A = [m \ n], B = [-n \ -m] \text{and} \ C = \begin{bmatrix} m \\ -m\end{bmatrix} \)1. CA = CB2. AC = BC3. C(A + B) = CA + CBWhich of the above statements is/are correct?

A.
1 only
B.
2 only
C.
2 and 3
D.
1 and 2

Solution:

Concept:1). For the addition and subtraction of two matrices, the order of matrices should be equal.2). For the multiplication of two matrices, the number of columns in the first matrix should be equal to the number of rows in the first matrix.3). In the multiplication of two matrices, the order of the resultant matrix is such that the number of rows is equal to the first matrix, and the number of columns is equal to the second matrix.Calculation:Given:\(A = [m \ n], B = [-n \ -m] \text{and} \ C = \begin{bmatrix} m \\ -m\end{bmatrix}\)Statement I: CA = CBCA = \(\displaystyle \begin{bmatrix} m \\ -m\end{bmatrix} [m \ n ]\) = \(\begin{bmatrix} m^2 &mn \\[0.3em] -m^2 & -mn\\[0.3em] \end{bmatrix}\)CB = \(\displaystyle \begin{bmatrix} m \\ -m\end{bmatrix} [-n \ -m ]\) = \(\begin{bmatrix} -mn &-m^2 \\[0.3em] mn & m^2\\[0.3em] \end{bmatrix}\)CA ? CBStatement I is incorrect.Statement II: AC = BCAC = \(\displaystyle [m \ n ] \begin{bmatrix} m \\ -m\end{bmatrix}\) = m2 - mnBC = \(\displaystyle [-n \ -m ]\begin{bmatrix} m \\ -m\end{bmatrix}\) = m2 - mnStatement II is correct.Statement III: C(A + B) = CA + CBC(A + B) = \(\displaystyle \begin{bmatrix} m \\ -m\end{bmatrix} ([m\ \ \ n ]+[-n \ -m ])\) = \(\displaystyle \begin{bmatrix} m \\ -m\end{bmatrix} [m-n \ \ \ n-m ]\) = \(\begin{bmatrix} m^2-mn &mn-m^2 \\[0.3em] -m^2+mn & -mn+m^2\\[0.3em] \end{bmatrix}\)CA + CB = \(\begin{bmatrix} m^2 &mn \\[0.3em] -m^2 & -mn\\[0.3em] \end{bmatrix}\) + \(\begin{bmatrix} -mn &-m^2 \\[0.3em] mn & m^2\\[0.3em] \end{bmatrix}\) = \(\begin{bmatrix} m^2-mn &mn-m^2 \\[0.3em] -m^2+mn & -mn+m^2\\[0.3em] \end{bmatrix}\)Statement III is correct.? Both Statement II and Statement III are correct.

For more questions,

Click Here

Download Gyanm App

free current affairs for competitive exams

Scan QR code to download our App for
more exam-oriented questions

free current affairs for competitive exams

OR
To get link to download app

Thank you! Your submission has been received. You will get the pdf soon. Call us if you have any question: 9117343434
Oops! Something went wrong while submitting the form.