Finding eqautions of lines

extrakrispy101

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Apr 16, 2007
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I am in Pre-Geometry (some algebra work and some geometry work).No matter how much my techer goes over these problems with me, I can't seem to remember how to do them right. Midterms are tomorrow and I am nowhere near ready ... Here it is.. I hope someone can help me!

Find the Eqaution of the Line Given the Follwing Points
(1,1) and (0,0)
 
Hi extrakrispy, welcome to the forums!

Finding the line that goes through those points, is easy..and fun!

First we must find the slope of the line that "will" pass through those points. Slope is defined by the "rise" over the "run" up and then over... lets find that rational!

The slope of the line is going to be (y2-y1)/(x2-x1)
You have two ordered pairs of the form (x,y) so, with two ordered pairs, we can name each x and y value, (x1,y1) and (x2,y2)

Plugging in those values into our formula: slope = (y2-y1)/(x2-x1) = (0-1)/(0-1) = -1/-1 = 1/1 = 1 SO You have a slope of 1

Now use the "point-slope" form of the equation for a line, and, (just as you plugged in the x1,x2,y1 and y2 values earlier) you will recognize their placement in below the equation:

y-y1=slope(x-x1)

we know the slope is 1. We know y1 = 1 and x1 = 1 so:

y-1 = 1(x-1)
y-1 = 1x-1
x-1+1 = 1x-1+1

So we have found the line with slope "1" through the points (1,1) and (0,0) to be
y = 1x, or simply y = x

Cheers, I hope this helped you!

If you are still confused, please post exactly where you are stuck, and the steps you took.

John.
 
Thanx sooo much! It did help. I sort of knew how to do it, but not completely, and you really helped me!!!! Thanx again!
 
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