Answer:
None of the above. (Ask your teacher to show you how to work this problem.)
Explanation:
Since the results are identical, the matrix of the next three rolls will look exactly like this matrix. (A)
The matrix of all 6 rolls will look like a 6-row matrix with the bottom 3 rows identical to the top 3 rows.
Adding or multiplying A by a constant will not produce these results.
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You can replicate columns using matrix multiplication, so you can transpose A, multiply it by a suitable version of an identity matrix, then transpose the result:
((A^T)·[I | I ])^T will turn the 3-row matrix to a 6-row matrix where I is a 3x3 identity matrix. I've used [I | I] here to mean the 3x3 identity matrix is itself replicated horizontally to make a 6-column matrix. ^T indicates transpose.