Question 1161522: Is it C? I want to check my answer.
Matrix C has the dimensions 7 X 2 and Matrix D has the dimensions 2 X 7. Determine the dimensions of the matrix CD, if it is possible. Explain why if it is not.
A. Matrix CD would have the dimensions 2 X 2
B. Matrix CD would have the dimensions 2 X 7
C. Matrix CD would have the dimensions 7 X 7
D. These matrices cannot be multiplied because their dimensions don't align.
The question is provided in the link here: https://i.imgur.com/Mskgwc3.png
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849)   (Show Source):
You can put this solution on YOUR website!
You can only multiply two matrices if their dimensions are compatible , which means the number of columns in the first matrix is the same as the number of rows in the second matrix.
Matrix C has the dimensions 7 X 2 and Matrix D has the dimensions 2 X 7=>their dimensions are  compatible
so, answer is:
D. These matrices cannot be multiplied because their dimensions don't align.
Answer by ikleyn(52781)  (Show Source):
You can put this solution on YOUR website! .
The post by @MathLover1 consists of two statements and a conclusion.
Of these two statements, the first one is correct, but the second contradicts to the first one and is INCORRECT.
Her conclusion is INCORRECT, too.
The correct solution to the problem is below.
I used the text by @MathLover1, by re-edited it to make it correct.
Solution
You can only multiply two matrices if their dimensions are compatible , which means the number of columns
in the first matrix is the same as the number of rows in the second matrix.
Matrix C has the dimensions 7 X 2 (two columns) and Matrix D has the dimensions 2 X 7 (two rows).
So, their dimensions are compatible for multiplication in this order.
Therefore, the ANSWER is:
C. Matrix CD has the dimensions 7 X 7.
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Solved.
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