If A as m×n matrix with rank n, and B as n×p matrix with rank p. Then the rank of matrix C=AB is __________ .
(D) None of these.
Explanation: The conditions from the hypothesis imply that m≥n≥p. One knows that,
rank(AB) ≤ min(m,p) = p
On the other side, from Sylvester Rank Inequality we get,
p = n+p−n ≤ rank(AB)
rank(AB) = p
Option (C) is correct.
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