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| 1. |
what is the value of n so that n+2, 5n+1, n+11 will form a geometric sequence? find the sum the first three terms of given sequence. |
| Answer» FIRST 3 terms=3,6,12 sum =21or-7/8+2,-5*7/8+1 and -7/8+11or 9/8, 27/8 and 81/8,sum=117/8Step-by-step EXPLANATION:n+2, 5n+1, n+11 are in GPso ( 5n+1)²=(n+2)((n+11)=25n²+10n+1=n²+13n+2224n²-3n-21=08n²-n-7=08n²-8n+7n-7=08n(n-1)+7(n-7)=0(n-1)(8n+7)=0n=1 or -7/8First 3 terms=3,6,12 sum =21or-7/8+2,-5*7/8+1 and -7/8+11or 9/8, 27/8 and 81/8,sum=117/8 | |