Solve for x and y:

(x,y)(1,2)=(-1,8)

this is not a valid matrix multiplication

If you want the dot product of two vectors, then x = -1, y = 4
If you meant to add the two pairs, then x = -2, y = 6

Maybe you should clear things up a bit ...

Question is, find values of x and y.

well, yeah, I got that when you said "Solve for x and y."

But solve what? Exactly what is involved here? Did you even read what I asked, and understand why I'm unclear on just what it is you want?

that notation is not something I've seen before.
points? vectors? Is there supposed to be an operator in there, like
(x,y)+(1,2)=(-1,8)
(x,y)-(1,2)=(-1,8)
(x,y)•(1,2)=(-1,8)
or something else?

To solve for x and y in the equation (x,y)(1,2)=(-1,8), we can use the concept of vector equality.

In a vector equation, we equate the corresponding components of two vectors to each other. In this case, we have the equation:

x * 1 + y * 2 = -1
x * 1 + y * 2 = 8

Now, we can solve this system of equations using any method like substitution, elimination, or matrices. Let's use substitution:

From the first equation, we can isolate x:

x * 1 + y * 2 = -1
x = -1 - y * 2

Substitute this expression for x in the second equation:

(-1 - y * 2) + y * 2 = 8
-1 - y * 2 + y * 2 = 8
-1 = 8

This contradicts the equation, which means there is no solution that satisfies both equations. Therefore, the system is inconsistent, and there are no values for x and y that satisfy it.