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If P, Q and R are matrices of order 2x3, 3x5 and 5x3 respectively. Then which of the following are valid?

(A) P Q R

(B) P R Q

(C) Q R

(D) R Q

(E) P R

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 1

Matrix P: 2×3 (2 rows, 3 columns)

Matrix Q: 3×5 (3 rows, 5 columns)

Matrix R: 5×3 (5 rows, 3 columns)

For two matrices to be multiplied, the number of columns in the first matrix must equal the number of rows in the second matrix.

If Matrix A is m×nm \times n and Matrix B is p×qp \times q, then A×BA \times B is valid when n=pn = p, with result being m×qm \times q.


(A) P Q R

Can P×Q be computed?

P is 2×32 \times 3, Q is 3×53 \times 5

Columns of P (3) = Rows of Q (3)

P×QP \times Q gives a 2×52 \times 5 matrix

Can (PQ)×R be computed?

PQPQ is 2×52 \times 5, R is 5×35 \times 3

Columns of PQ (5) = Rows of R (5)

Final result: 2×32 \times 3 matrix

Valid


(B) P R Q

Can P×R be computed?

P is 2×32 \times 3, R is 5×35 \times 3

Columns of P (3) ≠ Rows of R (5)

Invalid


(C) Q R

Q is 3×53 \times 5, R is 5×35 \times 3

Columns of Q (5) = Rows of R (5)

Result: 3×33 \times 3 matrix

Valid


(D) R Q

R is 5×35 \times 3, Q is 3×53 \times 5

Columns of R (3) = Rows of Q (3)

Result: 5×55 \times 5 matrix

Valid


(E) P R

P is 2×32 \times 3, R is 5×35 \times 3

Columns of P (3) ≠ Rows of R (5)

Invalid


Valid expressions: (A), (C), and (D)

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