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Set 6 Q27

Expert replies
Source: — Data Sufficiency |

by josephcho77 » Thu Oct 04, 2007 7:33 am
1) you can get the equation y = 4x – 3 using the points (-1, -7)and(2, 5)
The slop is positive

2) y = 4x – 3 (the slop is positive)

Answer is "D"
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by arocks » Thu Oct 04, 2007 8:54 am
I understand statement B. Could you elaborate stmt. A. How did you get the equation? Does the line pass through origin - how do we know?

Tnx.
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by gabriel » Thu Oct 04, 2007 9:59 am
arocks wrote:I understand statement B. Could you elaborate stmt. A. How did you get the equation? Does the line pass through origin - how do we know?

Tnx.
the equation of a line is given by y=mx+c, over here m is the slope and c is the y intercept ..

the given line passes thru the points (-1, -7) and (2, 5)

So we have 2 equations ,

for (-1, -7) we have -7= -1*m+c and
for (2, 5) we have 5 = 2m +c

... solve the 2 linear equations simultaneously to get values of m and c .. hope that helps ..
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by agps » Thu Oct 04, 2007 10:05 am
actually it's easier than that. the slope is given by the equation (y2-y1)/(x2-x1).

in this case
(-1, -7) and (2, 5)

(5-(-7))/(2-(-1)) = 12/3 = 4
or
((-7)-5)/((-1)-2) = -12/-3 = 4
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by arocks » Fri Oct 05, 2007 8:42 am
Thanks guys. Great responses....Its clear now!
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