What is the seventh term of following series: 5+6i, 7+13i, 11+32i, 19+69i, 35+130i, ....

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26 Jun 2017 Series

What is the seventh term of following series:

5+6i, 7+13i, 11+32i, 19+69i, 35+130i, ....

OPtion

1) 56 + 256i
2) 67 + 121i
3) 56 + 221i
4) 68 + 216i
5) 67 + 227i
6) 67 + 221i
7) 56 + 227i
8) 131 + 248i
9) 68 + 221i
10) None of these

Solution

The complex number is formed by two series:
Real part series is:
5, 7, 11, 19, 35, 67, 131
nth term is 2^n+3 = 2^7+3 = 131

Imaginary part is:
6, 13, 32, 69, 130, 221
nth term = n^3+5
7th term = 7^3+5 = 343+5 = 348

Hence 6th term 131+348i

Correct Option: 10 Best Solution (5)

Mukund Manohar   7 years AGO

Number Series without i part
5,7,11,19,35
5 + 2^1 = 7
7 + 2^2 = 11
11 + 2^3 = 19
19 + 2^4 = 35
35 + 2^5 = 67
67 + 2^6 = 131
Seventh term without i part = 131
Number Series with i part
6,13,32,69,130
1^3 + 5 = 6
2^3 + 5 = 13
3^3 + 5 = 32
4^3 + 5 = 69
5^3 + 5 = 130
6^3 + 5 = 221
7^3 + 5 = 348
Seventh term with i part = 348i
Seventh term of the given series = 131 + 348i

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tumati koushik   7 years AGO

for abcissa, adding go on with 2,4,8,16,32,64...
so abscissa are 5,7,11,19,35,67,131.
for mantissa it is n^3+5
so mantissa are 6,13,32,69,130,221,348
so the 6th term is 67+221i
7th term is 131+348i

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Dhivya   7 years AGO

For the real part the sequence is difference multiplied by 2,so 131 and for imaginary part it is n^3+5.So 7th term should be 348.

So option 10:none of these

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Krishna Porwal   7 years AGO

in real part series is +2 , +4 , +8 , +16 , +32 as the seventh term is 131 is correct to option 8 but in imaginary part the series is +7 , +19 , +37 , +61 means difference between two terms is +12 , +18 , +24 in this way the seventh term is 348 which is not given in any option so answer is none of these

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krishnateja   7 years AGO

5,7,11,19,35, next is 67 differences are in power of 2 and difference of numbers like 5+6i is 1 simillarly we get 1,6,21,50,95 calculate difference of difference u get finally ans as 67+229i

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