SOLUTION: how do I find a proportion using points on a graph?

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Question 652069: how do I find a proportion using points on a graph?
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
This is how you write a direct proportion. The symbol in the middle is the Greek letter alpha.
x+%28alpha%29y

It reads: x is directly proportional to y.

It means: By whatever factor x+changes, y changes by the same factor.
Here is an example of a point you can put on a graph. The point is (x1, y1) and it has coordinates (1, 1).
Coordinates for second point (x2, y2) are (3, 3)
as we can see, x changes by a factor of 3. That is, x1 times a factor of 3 equals x2, and
as we can see, y changes by a factor of 3. That is, y1 times a factor of 3 equals y2
Therefore, x is directly proportional to y, x+%28alpha%29y.

Also, x could be inversely proportional to y. It means: By whatever factor x changes, y changes by the inverse of that factor. (Or you could say, “by the reciprocal of that factor”.)
in example above x changes by factor 3; so, y changes by the inverse of that factor which is 1%2F3.