InterviewSolution
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Ifthecoefficient of(2r + 1 )thterm and(r + 2 )thterm inthe expansionof(1 + x ) ^(43 )areequal, then r is equalto |
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Answer» 12 Co -efficientof` T _ (2r + 1 ) `=co- efficient of` T _ (r + 2 ) ` ` RARR ""^(43)C_(2r)=""^(43)C_( r +1 ) ` `rArr2r=r + 1or2r+r+ 1=43 [because""^nC_r =""^nC_( N -r ) ] ` ` rArrr= 1or 3R+ 1=43 ` ` 3r=42` `r =14 ` `thereforer= 1orr=14` |
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