Question:

if $A = \begin{bmatrix}4&1&0\\ 1&-2&2\end{bmatrix} , B = \begin{bmatrix}2&0&-1\\ 3&1&x\end{bmatrix} , C = \begin{bmatrix}1\\ 2\\ 1\end{bmatrix}$ and $D =\begin{bmatrix}15+x\\ 1\end{bmatrix}$ such that $(2A -3B)C=D$, then $x$ =

Updated On: Jul 6, 2022
  • $3$
  • $-4$
  • $-6$
  • $6$
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is C

Solution and Explanation

$(2A - 3B) C =D$ $\Rightarrow\left[2\begin{bmatrix}4&1&0\\ 1&-2&2\end{bmatrix}-3 \begin{bmatrix}2&0&-1\\ 3&1&x\end{bmatrix}\right] \begin{bmatrix}1\\ 2\\ 1\end{bmatrix} =\begin{bmatrix}15+x\\ 1\end{bmatrix}$ $\Rightarrow\begin{bmatrix}2&2&3\\ -7&-7&4-3x\end{bmatrix} \begin{bmatrix}1\\ 2\\ 1\end{bmatrix} =\begin{bmatrix}15+x\\ 1\end{bmatrix}$ $\Rightarrow \begin{bmatrix}9\\ -17-3x\end{bmatrix} = \begin{bmatrix}15+x\\ 1\end{bmatrix} \Rightarrow x = -6$
Was this answer helpful?
0
0

Concepts Used:

Matrices

Matrix:

A matrix is a rectangular array of numbers, variables, symbols, or expressions that are defined for the operations like subtraction, addition, and multiplications. The size of a matrix is determined by the number of rows and columns in the matrix.

The basic operations that can be performed on matrices are:

  1. Addition of Matrices - The addition of matrices addition can only be possible if the number of rows and columns of both the matrices are the same.
  2. Subtraction of Matrices - Matrices subtraction is also possible only if the number of rows and columns of both the matrices are the same.
  3. Scalar Multiplication - The product of a matrix A with any number 'c' is obtained by multiplying every entry of the matrix A by c, is called scalar multiplication. 
  4. Multiplication of Matrices - Matrices multiplication is defined only if the number of columns in the first matrix and rows in the second matrix are equal. 
  5. Transpose of Matrices - Interchanging of rows and columns is known as the transpose of matrices.