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coordinate geometry

by cmr209 » Tue Aug 11, 2009 2:14 am
In the xy-coordinate system, if (a,b) and (a + 3, b + k) are two points on the line defined by the equation x = 3y - 7, then k = ?

A) 9

B) 3

C) 7/3

D) 1

E) 1/3


OA - D
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by truplayer256 » Tue Aug 11, 2009 4:18 am
x=3y-7

Re-write in y=mx+b form.

(x+7)/3=y

x/3+7/3=y

slope=m=1/3

Slope=y2-y1/x2-x1

1/3=b+k-b/a+3-a

1/3=k/3

k=1

D is correct.
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by cmr209 » Tue Aug 11, 2009 11:40 pm
Ah, that's better than the book explained. Thanks!
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