Question

Can anyone check my answer to see if I got it correct please?

Answer:

12 -6
-3 21

Answer 1

Looks good to me!
Since you're multiplying the entire matrix by a constant value, the result is a matrix of the same dimensions with each entry equal to the original multiplied by the constant.

Since the original was
[4, -2
-1, 7]
and the constant multiple was 3, the result would be
[4*3, -2*3
-1*3, 7*3]
Which resolves to
[12, -6
-3, 21]
Just as you said

Answer 2

Thank you!

Answer 3

No problem :)