Question

How do you multiply `((1, 3))` with `((-1, 2, 2, 4))`?

Answer 1

You can't.

Explanation:

Perhaps one of the following was intended:

Possibility 1
Multiply `((1,3))` by `((-1,2),(2,4))`
Remember we multiply "rows" by "columns"
There is only one row: `((1,3))`
but two columns: `((-1),(2))` and `((2),(4))`

`((1,3))xx((-1,2),(2,4))`

`color(white)("XXX") = ((1xx(-1)+2xx2,1xx2+3xx4))`

`color(white)("XXX")=((3,14))`

Possibility 2
Multiply `((1),(3))` by `((-1,2,2,4))`
I've left this one undone since I think it is less likely to be what is intended.

Remember:
For matrix multiplication,
`color(white)("XXX")`the number of entries in each row that you are multiplying
`color(white)("XXXXXX")`must be equal to
`color(white)("XXX")`the number of entries in each column that you are multiplying by