Question 262592: Hi,
I am trying to help my nieces with their homework, but I don't have much information to go by and it has been awhile since I played with equations.
Anyhow, maybe one of you know more what about what they are looking for or at least give me a clue.
I think they are trying to find the equation that by replacing the value IN, the result should match the OUT.
e.g. X + Y = Z (Where X=IN, & Z=OUT) makes sense? sorry if it doesn't.
I know is hard to pick from very little information.
:)
IN OUT
2 -1
3 +1
10 +15
15 +25
5 +7
Thanks a lot
Found 2 solutions by richwmiller, dabanfield:
Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website! your list is a list of x's and y's points on a graph (a line).
your nieces to to make an equation knowing the points.
pick two points (x[1],y[1]) and (x[2],y[2]) from the list.
using the 
where m is the slope.
then using y=mx+b
plug in either of the two points and the new m
and solve for b
now write y=mx+b with the new m and the new b
so that the equation looks something like
y=3x+4 but with different numbers
Have fun. Some of this should seem familiar to your nieces.
Answer by dabanfield(803)  (Show Source):
You can put this solution on YOUR website! 2 -1
3 +1
10 +15
15 +25
5 +7
If you make x the values in the IN column and y the corresponding values in the OUT column you can then plot the points (2,-1), (3,1), (10,15), (15,25) and (5,7) on an x-y axis.
These points all lie on a line except the point (5,7). The equation of the line in "slope-intercept" form is actually y = 2x - 5 where 2 is the slope of the line (I calculated the slope by selecting two of the points (e.g. (15,25) and (10,15) and taking the difference of the y values (25-15) and dividing by the difference of the corresponding x values (15-10). The slope then is (25-15)/(15-10) = 10/5 = 2.
If the last point had been (5,5) instead of (5,7) all the points would lie on this line.
I hope this helps.
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