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| physics chemistry maths science forums |
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![[Post New]](/templates/default/images/icon_minipost_new.gif) 4 Sep 2007 22:40:54 IST
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LET F(x) == sin (  /x) & D = { x: F(x) >0 } THEN D ==
A) (1/3 ,1/2) B) (1/5 , 1/4) C) (-1, -1/2) D) ALL OF THESE.
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4 Sep 2007 22:58:36 IST
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I guess it is A ..as sin 3A ==sinA ..and sin 2A=Sin0 both are in the 1 and 2nd quadrant...
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5 Sep 2007 13:19:55 IST
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i trhink it is A&B as d range of fx is +1 -1 & we reject -ve to satisfe D
option c wrong as if values of sinx -ve then fx being odd funtion will also b -ve but D restricts it...
i may b wrong but pl tell me d ans once u get it...
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......and miles 2 go before i sleep & miles 2 go before i sleep....... |
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5 Sep 2007 19:35:11 IST
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sin (  /x) >0 if /x  ( 2n , (2n+1) )
1/x (2n,2n+1)
x ( 1/(2n+1) , 1/2n)
putting n=1,2,-1 v get the answer
so (D) is the right answer
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