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New way of finding out equation of a line

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by gmatrant » Mon Nov 12, 2007 7:05 am
I have come across a point slope formula to calculate the equation of the line.
y-y1 = m(x-x1).
But i don't understand this approach

The explanation is from Kaplan's website
But in the explanation below I don't understand how he calculates the slope of the line. Why does he move 6 units to the right from the point marked (-6,-1). Can someone explain what is the approach here.
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Source: — Problem Solving |

by mschling52 » Mon Nov 12, 2007 8:12 am
He is trying to find the y-intercept of the line, which is the y-coordinate of the point where the line intersects the y-axis (in other words, the y-coordinate of the point where x=0). He moves six units to the right from the point (-6,-1) because moving 6 units to the right in the horizontal direction will get you to the point where x=0.
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by moneyman » Mon Nov 12, 2007 10:07 pm
When 6 points are moved to the right the line climbs by 11 1/4 then shouldnt the y intercept be 11 1/4?? Why is it 10 1/4??
Maxx
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by gmatrant » Tue Nov 13, 2007 1:36 am
moneyman wrote:When 6 points are moved to the right the line climbs by 11 1/4 then shouldnt the y intercept be 11 1/4?? Why is it 10 1/4??
11 1/4 up, so (6,-1) when moved along the slope i.e 11 1/4 is
11 1/4 + (-1) = 10 1/4.

Did you get it?
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by moneyman » Tue Nov 13, 2007 2:20 am
Oh yeah!! It completely makes sense now. I cant believe I dint notice that. Thanks
Maxx
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