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Analytical Geometry

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Joined:	16 Oct 2007
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27 Dec 2007 00:08:57 IST

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477

here is a question with answer.just explain me the step marked with (*)

None

1.a,b,c form a G.P with common ratio r then the sum of the ordinates of the points of intersection of the line ax+by+c = 0 and x+2y²=0 is:

ans:

> -(by + c) / a + 2y^{2_{= 0}}

^{_{> 2ay}2}^{_{- by - c = 0}}

_{^{> (*) y1 + y2 = b/2a = ar/2a = r/2}}

_{^{in the 3rd step how y1 + y2 = b/2a?}}

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Comments (4)

ashima .....

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Joined: 20 Dec 2007

Posts: 35

27 Dec 2007 12:01:55 IST

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ur doubt is correct it must be ( -b/2a) . positive kaise aayega. may be printing mistake???????

abc def

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Joined: 27 Oct 2007

Posts: 102

27 Dec 2007 18:39:38 IST

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R1 + R2 = -b/2a

I don't understat whats the the mistake here

ashima .....

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Joined: 20 Dec 2007

Posts: 35

27 Dec 2007 20:20:39 IST

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the mistake is y1+y2 must be -b/2a but it is given +b/2a

kanika gupta

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Joined: 31 Aug 2007

Posts: 117

2 Jan 2008 11:23:28 IST

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hey guys its correct .

if eqn is ax^2 + by^2 +c =0

then sum of roots is -b/a & not b/a

pls rate if satisfied

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