Question:

If \(\begin{vmatrix}1&-1&x\\1&x&1\\x&-1&1\end{vmatrix}\) has no inverse, then the real value of \(x\) is

Updated On: Aug 23, 2023
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The Correct Option is D

Solution and Explanation

\(\begin{vmatrix}1 & -1 & x \\ 1 & x & 1 \\ x & -1 & 1\end{vmatrix}\) 
Has no inverse;
\(\Rightarrow|A|=0\)
\(x+1+1(1-x)+x\left(-1-x^{2}\right)=0\)
\(x+1+1-x-x-x^{3}=0\)
\(x^{3}-x-2=0\)
\(\Rightarrow x^{3}+2 x-x-2=0\)
\(\left(x^{2}-1\right)(x+2)=0\)
\(\Rightarrow x=\pm 1, x=-2\) 
Real value of \(x=1\)

 
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Concepts Used:

Transpose of a Matrix

The matrix acquired by interchanging the rows and columns of the parent matrix is called the Transpose matrix. The transpose matrix is also defined as - “A Matrix which is formed by transposing all the rows of a given matrix into columns and vice-versa.”

The transpose matrix of A is represented by A’. It can be better understood by the given example:

A Matrix
A' Matrix
The transpose matrix of A is denoted by A’

Now, in Matrix A, the number of rows was 4 and the number of columns was 3 but, on taking the transpose of A we acquired A’ having 3 rows and 4 columns. Consequently, the vertical Matrix gets converted into Horizontal Matrix.

Hence, we can say if the matrix before transposing was a vertical matrix, it will be transposed to a horizontal matrix and vice-versa.

Read More: Transpose of a Matrix