P is a 3 × m matrix, Q is an n × 4 matrix and R is a 2 × 3 matrix. If RPQ is defined, which of the following is true?

Question 58

HardOriginal question

$P$ is a $3 \times m$ matrix, $Q$ is an $n \times 4$ matrix and $R$ is a $2 \times 3$ matrix. If $RPQ$ is defined, which of the following is true?

m = n

, and

RPQ

3 \times 4

Correct answerYour answer

m = 3

, and

RPQ

2 \times 4

Correct answerYour answer

n = 3

, and

RPQ

2 \times m

Correct answerYour answer

m = n

, and

RPQ

2 \times 4

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

$RP$ is defined, since $R$ has 3 columns and $P$ has 3 rows, and it is $2 \times m$ .
$(RP)Q$ then needs $m = n$ , and it is $2 \times 4$ .

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