Question:

If $W=\{\left(\begin{matrix}x& y\\ z& 0\end{matrix}\right):x,y,z\in R\}$ is a subspace of the vector space $M_{2}$ of $2\times2$ matrices over the field of real numbers R, then $dimW=_$

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Dimension = Number of arbitrary constants in the general form of the vector.
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The Correct Option is C

Solution and Explanation

Step 1: Concept
The dimension of a subspace is the number of free variables or basis vectors needed to represent any element in that space.

Step 2: Meaning

Any matrix in $W$ can be written as: $x\left(\begin{matrix}1& 0
0& 0\end{matrix}\right) + y\left(\begin{matrix}0& 1
0& 0\end{matrix}\right) + z\left(\begin{matrix}0& 0
1& 0\end{matrix}\right)$.

Step 3: Analysis

There are three independent parameters ($x, y, z$) that define the set, and the three matrices shown above form a basis for $W$.

Step 4: Conclusion

Since there are three vectors in the basis, the dimension is 3. Final Answer: (C)
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