# Find unknown matrix element using elementary row operation?

$$A=\left(\begin{matrix}x & 5 & x \\ 1 & 3 & -2\\ -2 &-2 &2 \end{matrix}\right)$$

$$B=\left(\begin{matrix}0 & 0 & 21 \\ 1 & -1 & -14\\ 0 &\frac{4}{3} &4\end{matrix}\right)$$

Given if B can be obtained From A by applying finitely many basic row operation then what is value of x ?

One thing I did not understand the value of x be unique ]

If this is true then we have $$\det{(A)}=\det{(B)}$$ hence $$6x-2x+20+6x-4x-10=28$$ $$6x=18$$ $$x=3$$
Can you find an $$x$$ such that the two matrices have the same determinant?