Question

If $\left[\begin{array}{ccc}x& 1& 1\\ 2& 3& 4\\ 1& 1& 1\end{array}\right]$ has no inverse, then $x=$

• A. $-4$
• B. $-2$
• C. $1$
• D. $-3$

Answer 1

The correct option is C $1$

We know that, If Det$=0$ there is no inverse

$\Rightarrow D=x(3-4)-1(2-4)+1(2-3)=0$

$\Rightarrow -x+2-1=0$

$\Rightarrow x=1$