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Q.Consider the matrices P = [[3, -1, 2], [-2, 1, 4]], Q = [[4, -2, 1], [-5, 3, 1]] and R = [[3, 0, 0], [0, 3, 0], [0, 0, 3]].
(i) The order of the matrix PR is ______.
(1)
(ii) Show that PR = 3P.
(1)
(iii) Find 3P + Q. (1)
Kerala DhseKerala DHSE Plus Two Board 2026Subjective· 3mImportance★★★★★
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Start your 14-day free trial to unlock the full solution →P is 2×3 and R is 3×3, so PR is 2×3; since R = 3I, multiplying any matrix by R just scales it by 3, giving PR = 3P directly.
- Order of PR. P has order and R has order . For the product PR to be defined, the number of columns of P (3) must equal the number of rows of R (3) — it does. The product then has order (rows of P) × (columns of R) = .
- Show PR = 3P. Note , where is the identity matrix. So …
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