When a line passes through points (x1, y1) and (x2, y2), It can be written in the form:
y = mx + c ..... (1)
where m = (y2 - y1)/(x2 - x1)
We can find c and with that the equation.
Here, m = (-6 + 1)/(10 - 5) = -5/5 = -1
Using (1), we get,
y = -x + c ..... (2)
(5, -1) is a solution of the equation, so put x = 5 and y = -1 in the equation (2) to get c,
-1 = -5 + c
c = 4
We have our equation,
y = 4 - x
-----> x + y = 4
DONE
2007-07-16 14:22:41
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answer #1
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answered by Akilesh - Internet Undertaker 7
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The y-y1 over x-x1 is the slope of the line. Remember the equation of a line is y=mx+b where m is the slope and b is the y-intercept. Calculate the slope first. Let's use (5,-1) as (x1 ,y1). m = [-6-(-1)]/[10-5] = -5/5 = -1. Now, put this in for m into your equation. y = -1x+b. Choose one of the points you started with to plug in for x and y, and solve for b.
I'll use (5,-1): -1=-1*(5)+b
-1=-5+b
4=b
Now you just have to plug in:
y=-1x+4 (or, you can get rid of the 1 to have y = -x+4)
2007-07-16 14:18:59
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answer #2
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answered by korie55 2
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