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Sequence and Series
Q. Find the 8th term ...
3,11,31,69,131
Read Solution (Total 11)
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- 1^3+2=3,2^3+3=11,3^3+4=31,4^3+5, similarly 8th number 8^3+9=521
- 11 years agoHelpfull: Yes(44) No(1)
- the right ans is 521
- 11 years agoHelpfull: Yes(21) No(0)
- 1^3+2=3
2^3+3=11
3^3+4=31
4^3+5=69
5^3+6=131
therefore 6^3+7=223 - 11 years agoHelpfull: Yes(6) No(6)
- T(n)= n^3 + (n+1)
So,
T(1) = 1^3 + (1+1) = 3
T(2) = 2^3 + (2+1) = 11
T(3) = 3^3 + (3+1) = 31
T(4) = 4^3 + (4+1) = 69
T(5) = 5^3 + (5+1) = 131
T(6) = 6^3 + (6+1) = 223
T(7) = 7^3 + (7+1) = 351
T(8) = 8^3 + (8+1) = 521
Hence , The required answer is 521 - 11 years agoHelpfull: Yes(4) No(1)
- 3 11 31 69 131 223 351 521
8 20 38 62 92 128 170
12 18 24 30 36 42
so 521 is d answer.... - 11 years agoHelpfull: Yes(3) No(1)
- 3 11 31 69 131
8 20 38 62
12 18 24
6 6
that means 24=6=30
30=62=92
92+131=223
ans is 223 ??? - 11 years agoHelpfull: Yes(2) No(2)
- sorry this is the 6 th term....521 is the ans.
- 11 years agoHelpfull: Yes(2) No(0)
- the difference between successive terms is 8,20,38,62 whose difference in turn is 12,18,24 in ap. and the next term of this ap is 30. so the successive difference between terms shud be 62+30=92. therefore nxt term is 131+92=223 ans.
- 11 years agoHelpfull: Yes(1) No(1)
- 1^3 + 2=3
2^3 + 3=11
3^3 +4=31
4^3+5=59
5^3+6=131
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8^3+9=521 - 11 years agoHelpfull: Yes(1) No(0)
- 521 as series follow a^3+n
- 7 years agoHelpfull: Yes(1) No(0)
- 1^3+2=3,
2^3+3=11,
3^3+4=31
....
similarly 8th number
8^3+9=521 - 9 years agoHelpfull: Yes(0) No(0)
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