Answer:
The slope is 4
Step-by-step explanation:
So the formula is y=mx+b. M is the slope and b would be your y intercept. So the slope is 4. (I just did this in class)
Let
and
. Then


and


The expression under the square root can be rewritten as

Recall that

so that

and assuming
and
, we end up with

so that

as required.
The 3rd and 5th systems of equations are the answer.
Point A is at (3,-1), so all you do is input 3 for x and -1 for y into all the equations. For the systems to work, both equations must work with (3,-1).
Only the third and fifth boxes work.