# Math Help - Equality

1. ## Equality

What do I need to do to solve what the value of k does equality hold:

|1 0 4| |1 0 4|
|3 0 9|=k |3 0 9|?
|5 5 20| |5 5 20|

2. Originally Posted by mike1
What do I need to do to solve what the value of k does equality hold:

|1 0 4| |1 0 4|
|3 0 9|=k |3 0 9|?
|5 5 20| |5 5 20|
are you trying to write matrices?

notice that the matrix (or determinant of a matrix, not sure which you are doing) on the left is the same as on the right, except for the k. so we must have k=1, otherwise the equality wouldn't hold

3. I am trying to do a matrices. I think my answer would be 1, but I am confused about the question too.

4. Originally Posted by mike1
I am trying to do a matrices. I think my answer would be 1, but I am confused about the question too.
well, one way to look at it is that the k is a scalar multiple, so you can multiply each element within the matrix by k, then to have equality, you would equate corresponding components.

so 1 = 1k
0 = 0k
4 = 4k
.
.
.
and so on

then the obvious answer for k is 1

5. Originally Posted by mike1
I am trying to do a matrices. I think my answer would be 1, but I am confused about the question too.
The answer is k=1 because both matrices are unchanged.