You have 2 points, (x1,y1) and (x2,y2) and you want to find the equation of the line that goes through these points.
The first thing you want to do is find the slope.
slope is rise/run so m = (y1-y2)/(x1-x2)
For slope intercept form , y = mx + b
where m is the slope, and b is the y intercept
now that you have found the slope, you can solve for b, the y intercept by plugging in your value for m and one of the given points, either (x1,y1) or (x2,y2).
For point slope form, y - K = m(x - H)
m is the slope, and (H,K) is a point that the line passes through.
Since you have already calculated the slope, m, for the slope intercept form, you're already almost done. All you have to do is plug in the point (x1,y1) or (x2,y2). In your question, you are asked for the point slope form of just point (6,2).
2006-11-18 15:09:23
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answer #1
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answered by Pony 2
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1st, the slope of the line passing through 2 points is the difference in y-value divided by the difference in x-value, (Y2 - Y1)/(X2 - X1), so the slope of this line is
(2 - -1)/(6 - 1) = (2 + 1)/5 = 3/5
To arrive at the point-slope form, pick one of the points (say (6,2))and set up the ratio
(y - 2).... 3
-------- = -- , then
(x - 6).... 5
(y - 2) = (3/5)(x - 6)
At this point you can get rid of the slope fraction, giving
5(y - 2) = 3(x - 6), or 5y - 10 = 3x - 18, or 5y = 3x - 8
To get to the slope-intercept form, you want y alone on the left, (y = mx + b), so divide through by 5 again, giving
y = (3/5)x - 8/5 ("fractional form"), and
y = 0.6x - 1.6 ("decimal form")
You can really normalize your fractions and do your distributions any time you want, but maintaining fractional form helps me to visualize the process, and is usually exact. You don't have to worry about where to round numbers until you have your final solution.
2006-11-18 14:55:29
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answer #2
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answered by Helmut 7
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m= 3/5
b= 8/5
2006-11-18 17:46:17
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answer #3
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answered by Angel Girl 5
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slope= (y1-y2)/(x1-x2)
(-1-2)/(1-6)= -3/-5=3/5
y=mx+b
2=3/5(6)+b
2=18/5 +b
b= -8/5
y=3/5x-8/5
My bad!
2006-11-18 14:37:10
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answer #4
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answered by 7
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I just want to say that yupchagee has the correct answer
Now everyone is correct :)
2006-11-18 14:45:04
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answer #5
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answered by Shawn 1
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slope=(2-(-1)/(6-1)=3/5
y=(3/5)x+b
-1=(3/5)+b
-8/5=b
b=-8/5
y=3x/5-8/5
2006-11-18 14:34:24
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answer #6
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answered by yupchagee 7
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