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The sum of first three terms of a G.P. is `(39)/(10)`and their product is 1. Find the common ratio and the terms. |
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Answer» Correct Answer - `r=5/2 or 2/5; 2/5, 1, 5/2 or 5/2, 1, 2/5` Let the three terms of the GP be `a/r, a` and `ar`. Then, `a/rxxaxxar=1 rArr a^(3)=1 rArr a=1`. So, the given terms are `1/r, 1` and r. `:. 1/r+1+r=39/10 rArr r+1/r=(39/10-1)=29/10` `rArr 10r^(2)+10=29r` `rArr 10 r^(2)-29r +10=0` `rArr (2r-5) (5r-2)=0` `rArr r=5/2` or `r=2/5` Hence, these terms are `2/5, 1, 5/2` or `5/2, 1, 2/5`. |
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