Algebra help: Linear functions, etc

[ViperMagic]

Ok, I understand precisly 0 of this, and I have a test tomorrow, and I need some help.

How do I take two points, put them into slop-intercept (I can find the slope, how do I get the intecept?) THen how do I take that and put it into standard form?

Say I have the points (-4,6),(0,0)

The slope would be -3/2, so ive got y=-3/2x+b. How do I find b (y intercept)?

Then how do I put that into standard form (Ax+By=C)?

 

[b0mbrman]

Use point slope to find the intercept. THe formula's as follows:

Given a point (x1,y1) and a slope m
(Y-y1) = m (X - x1)
Then isolate Y
Y = m (X - x1) + y1

Now you've got a point (0,0) so x1 would be 0 and y1 would be 0...just substitute that in

 

[MajesticMoose]

Do you under stand how to get slope? I can explain that too if you need me to.

Edit: For the Y-int, i may not have told you right about the Y-int. At any rate, since you already know that the line passes through the origin (0,0) you don't have solve anything.

 

[ViperMagic]

intecpt 0?

standard form 6x+4y=0?

Thanks fo rthe help btw

 

[ViperMagic]

I find slope, but after that my knoweldge falls like an undefined slope

 

[b0mbrman]

<< intecpt 0?
standard form 6x+4y=0?
Thanks fo rthe help btw >>


Oh wait...I'm an idiot. I saw the point (0,0) and couldn't tell you the intercept
<==--slow tonight (and every night )

 

[b0mbrman]

Yeah...that's right.

And don't forget that "6x + 4y = 0" is equivalent to saying "3x + 2y = 0"

 

[ViperMagic]

<< Yeah...that's right.

And don't forget that "6x + 4y = 0" is equivalent to saying "3x + 2y = 0" >>



Yeah thats in the back of my book. I was about to scream when i figured that out Would it be the same if I had 6x+4y=10, 3x + 2y = 10? I dont divide the right side?

 

[Yomicron]

<< Yeah thats in the back of my book. I was about to scream when i figured that out Would it be the same if I had 6x+4y=10, 3x + 2y = 10? I dont divide the right side? >>




nope, you gotta divide every term, on the left, and on the right.

 

[Mountain]

VIPER MAGIC IF YOU ARE STILL READING
I teach high school math.

I do what I call "Name that Dot" which means, what are the coordinates (x,y) for some point on a graph.

Question One. do you know what "equals" means? of course you do. SO:

the left side of the equation WILL "equal" the right side of the equation WHEN
you "substitute" the correct numbers for the letters "x" and "y"in the equation. Mathy people like to say that these numbers for x and y "Satify" the equation.

If a point(DOT) is "on" a line, then the Numbers for "x" and "y" in the "coordinate" (x, y)( the DOT's Name) will fit the equation perfectly and cause the right and left sides of the equation to be "equal".

If you are using the slope intercept form then it looks like y=mx+b.

You use two(2) points on the line to find the slope, so that a number can be put in place of the letter M.

Then use ANY point on the line (like maybe either of the two that you used for the slope formula) and notice what the "coordinates" for that point are. You can put the "y" part of the point's coodinate point in place of the "y" letter in the y=mx+b formula and the "x" part of the point's coordinate in place of the "x" letter in the same formula and you have replaced the letters y, x, and m with good numbers.

The only letter left to find is the "b" letter.

Play algebra until it is by itself on one side of the equation and you have "solved" the equation for "b".
LastLy and finally, rewrite the equation, using using the LETTERS "y" and "x" and put the slope number in place of "m" and the last number you found in place of "b".

Move the "mx" term to the extreme left of the "y" letter, yes you have crossed the equal sign and the "sign" changed on the 'mx" term.