1)

If rank of  $\begin{bmatrix}x & x&x \\x & x^{2}&x\\x&x&x+1 \end{bmatrix}$ is 1, then 


A) x=0 or x=1

B) x=1

C) x=0

D) $x\neq0$

Answer:

Option C

Explanation:

A= $\begin{bmatrix}x & x&x \\x & x^{2}&x\\x&x&x+1 \end{bmatrix}$ 

Since , rank A=1 , therefore atleast  one determined of order 1 should be  non-zero  and all the determinants of order 2 and 3 should be zero.

 If x=0 , then $A=\begin{bmatrix}0 & 0&0 \\0 & 0&0\\0&0&1 \end{bmatrix}$ , which have non-zero

 determinant of order 1 only.

If x=1, then  $A=\begin{bmatrix}1 & 1&1 \\1 & 1&1\\1&1&2 \end{bmatrix}$, which have a non-zero determinant of order 2, 

nearly $\begin{bmatrix}1 & 1 \\1 & 2 \end{bmatrix}$

 $\therefore$  x can  take value 0 only