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coordinate geometry

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coordinate geometry

by frizo » Mon Feb 16, 2009 11:16 am
m and n are the x and y coordinates, respectively, of a point in the coordinate plane. If the points (m, n) and (m+p, n+4) both lie on the line defined by the equation x = (y/2) - (2/5) , what is the value of p?


4/5

1

2

5

8


C
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by truplayer256 » Mon Feb 16, 2009 11:32 am
Rewrite x=(y/2)-(2/5) into slope intercept form
Slope intercept form= y=mx+b where m is the slope and b is the y-int.
2(x+2/5)=y
2x+4/5=y
Slope=2

The equation for slope is: y2-y1/x2-x1.
We know that the 2 points (m,n) and (m+p,n+4) must have a slope of 2 by doing the following:

(n+4-n)/(m+p-m)=2
4/p=2
4=2p
p=2 C
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by tini » Mon Feb 16, 2009 3:30 pm
the eqn of the line is x=y/2-2/5
substitute the coordinates of the first point:m=n/2-2/5
substitute the coordinates of the second point:m+p=(n+4)/2-2/5
or,n/2-2/5+p=(n+4)/2-2/5
or,p=2
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