# Thread: Question regarding Algebra - Slope intercept form

1. ## Question regarding Algebra - Slope intercept form

So I've been out of the loop of math for some 4 years, and now I'm back in college doing math. Everyone loves math!

So lets discuss something I'm wondering about.

y(2)-y(1)
________
x(2)-x(1)

Can this equation be reversed ?

Can we do

y(1)-y(2)
________
x(1)-x(2)

I'm under the assumption that you can, based only on the fact that in the previous week or two I swear I read something that told me you could, SO LONG as you remained uniform (ie didn't do y(2)-y(1) over x(1)-x(2)
But my buddy thinks you can't swap it.

Can I get some clarification?

(Yes I am aware that y=mx+b is the actual slope intercept form, but I'm discussing how to get it into that form)

2. This is the formula to find the slope, not slope intercept form. Slope intercept form is : f(x)=mx+b

As to your question, I don't really know. I doubt it though.

Also, after doing some reading around it looks like you can. The standard is just y2-y1 over x2-x1. No idea why.

3. Yes, you're able to swap Y2 and Y1 so long as the X's match up. You cannot do Y2-Y1/X1-X2.

For example:
You're points are (1,2) and (3,4)

Using Y2-Y1/X2-X1:
4-2/3-1
2/2
1.

Using Y1-Y2/X1-X2:
2-4/1-3
-2/-2
1.

Using Y1-Y2/X2-X1:
2-4/3-1
-2/2
-1.

So, as long as both the X's and Y's match up they can be put in any order.

4. Originally Posted by Nate17182
Yes, you're able to swap Y2 and Y1 so long as the X's match up. You cannot do Y2-Y1/X1-X2.

For example:
You're points are (1,2) and (3,4)

Using Y2-Y1/X2-X1:
4-2/3-1
2/2
1.

Using Y1-Y2/X1-X2:
2-4/1-3
-2/-2
1.

Using Y1-Y2/X2-X1:
2-4/3-1
-2/2
-1.

So, as long as both the X's and Y's match up they can be put in any order.
I was going to say that you couldn't because it was subtraction and 5-2 is not equal to 2-5. But then I remembered the signs end up canceling out anyways.

Math was a long time ago.

5. Question regarding why this is in Fun Stuff? Seriously.

6. I think so, they always just forced me to memorize "change in y over change in x". As long as your new format of the equation does the same thing, it'll yield the same number.

test both, that always works.

Originally Posted by suttie
Question regarding why this is in Fun Stuff? Seriously.
math is fun!

7. Originally Posted by suttie
Question regarding why this is in Fun Stuff? Seriously.
Anyone who thinks math is fun is clearly a cylon. This thread allows us to identify and destroy them before they can become a problem.

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