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![[Post New]](/templates/default/images/icon_minipost_new.gif) 30 Apr 2008 12:36:10 IST
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the eq whose roots r multiplied by 2 of those of 3x^2+5x-2=0 is
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30 Apr 2008 12:39:19 IST
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options r
a)3x^2+10x-8=0
b)x^2+5x+6=0
c)x^2-5x+6=0
d)x^2-5x-6=0
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DONT AIM FOR PERFECTION JUST ACHIEVE IT |
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30 Apr 2008 12:41:48 IST
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sum of the roots of the new equation is 2 times that of the earlier
so new sum = - 10 / 3
product of the roots = 4 times
so product is - 8/3
so the answer is A
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30 Apr 2008 12:42:46 IST
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thanx
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DONT AIM FOR PERFECTION JUST ACHIEVE IT |
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3x^2+5x-2 = 0
= x^2 - (sum of roots)x + (product of roots)
if roots are multiplied by two, it should become:
x^2 - 2(sum of roots)x + (2*2*product of roots)
so answer is
3x^2 + 2*5x - 2*4
= 3x^2 + 10x - 8 = 0
option (a)
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---------------------------------------------------------------
* Gaurav Ragtah ( aka Artemis Fowl )
* Agent 'G' [sniper] - SD-6 (Alliance of Twelve)
* Your friendly neighborhood spideyunlimited |
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30 Apr 2008 16:27:02 IST
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Suppose the given expression is f(x),Then the eqn whose roots are 'k' times that of the roots of f(x) is given by f(x/k)=0.here,k=2.
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MAKING A MISTAKE IS HUMAN BUT REPEATING IT IS IDIOTIC. |
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