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The value of $x$ for which all the eigen-values of the matrix given below are real is $$\begin{bmatrix} 10&5+j &4 \\ x&20 &2 \\4 &2 &-10 \end{bmatrix}$$

1. $5+j$
2. $5-j$
3. $1-5j$
4. $1+5j$