Coord - slopes

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Coord - slopes

by arocks » Mon Oct 15, 2007 1:32 am
Line K passes through point (n,-1). Is slope of K positive?

1). K passes through the origin point.
2). K passes through (1, n+2)


OA-C

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by samirpandeyit62 » Mon Oct 15, 2007 6:50 am
Line K passes through point (n,-1). Is slope of K positive?

1). K passes through the origin point.

slope = 0- (-1)/ 0-n = -1/n can be +ve or -ve based upon n

INSUFF

2). K passes through (1, n+2)

again slope = n+3/1-n can be +ve or -ve INSUFF

Combine

n+3/1-n = -1/n

n^2 +3n =-1 +n

i.e n^2 +2n +1 =0

i.e (n+1)^2 =0

n=-1

so slopw =-1/n =1/2 yes +ve

SUFF

C
Regards
Samir

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by arocks » Mon Oct 15, 2007 8:30 am
samirpandeyit62 wrote:Line K passes through point (n,-1). Is slope of K positive?

1). K passes through the origin point.

slope = 0- (-1)/ 0-n = -1/n can be +ve or -ve based upon n

................

n=-1

so slope =-1/n =1/2 yes +ve

SUFF

C
Thanks a lot...!!
A minor slip-up though...
slope=1 +ve... [-1/-1]

if this was a PS and asked to calculate slope - you would have extracted defeat from the jaws of victory;)....for lack of a better analogy!!

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by samirpandeyit62 » Mon Oct 15, 2007 8:47 am
Hey Arocks,
If this was a PS question, I'm sure 1/2 would not have been amongst the answer choices :D :D
Regards
Samir

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by arocks » Mon Oct 15, 2007 9:06 am
Absolutely...the other way to look at any slip-ups is that they would happen only to the experimental questions, so won't be marked!!

But you give great explanations...i was just trying to be a pain;)