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If three successive terms of as G.P. with commonratio `rgt1` form the sides of a triangle and [r] denotes the integral part of x the `[r]+[-r]=` (A) 0 (B) 1 (C) -1 (D) none of these |
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Answer» Correct Answer - C Let the sides of a triangle be `a,ar,ar^(2)`. Since, `rgt1`. Therefore, `ar^(2)` is the largest side. `:." "a+argtar^(2)` `rArr" "ar^(2)-a-arlt0` `rArr" "r^(2)-r=1lt0` `rArr" "(1-sqrt(5))/(2)ltrlt(1+sqrt(5))/(2)` `rArr" "1ltrlt(1+sqrt(5))/(2)rArr[r]=1" "[becausergt1]` Also, `-(1+sqrt(5))/(2)lt-rlt-1rArr[-r]=-2` Hence, [r]+[-r]=1-2=-1. |
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