Q1. Write a recursive formula for the geometric sequence whose third term is
fourth term is
and
.
Q2. Using the given explicit formula for the arithmetic sequence, find the 10th and 11th term
of the sequence.
an=
Q3. Write explicit formula for the sequence:
21,27,33,39,45,……..
Q4. You deposit $600000 in the bank Account paying 6% annual compound interest every
year and you withdraw $75000 at the end of every year. Write a recursive formula that
models the situation.
Q5. Using the given explicit formula for the arithmetic sequence, find the 31stand 75th term
of the sequence.
an=
Q6. Write a recursive formula for the geometric sequence whose ninth term is
eighth term is
and
Q7. Given the explicit formula of a geometric sequence find the first five terms of the
sequence.
Q8. Given the explicit formula of a geometric sequence find the first four terms of the
sequence.
Q9. Given the recursive formula for a sequence, find the explicit formula for the sequence.
an= an-1
a1=
Q10. Given the recursive formula for a sequence, find the explicit formula for the sequence.
an= an-1
a1=
Q11. Write explicit formula and recursive formula for the sequence:
4,15,26,37,48,…………
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Q12. Write explicit formula and recursive formula for the sequence:
9,23,37,51,65…………
Q13. A cup of coffee is initially at a temperature of 85º F. The difference between its
temperature and the room temperature of 45º F decreases by 8% each minute. Write a
function describing the temperature of coffee as a function of time.
Q14. Given first term of the sequence is 9 and common ratio=1/4, then derive the explicit
formula for this sequence. Also find sixth term of the sequence.
Q15. Given first term of the sequence is 11 and common ratio=-2, then derive the explicit
formula for this sequence. Also find first four terms of the sequence.
Q16. Given first term of the sequence is 21 and common ratio=-1/2, then derive the explicit
formula for this sequence. Also find first three terms of the sequence.
Q17. Write the recursive formula for the geometric sequence: 3,9,27,81,.......
Q18. Write the recursive formula for the geometric sequence: 4,20,100,500,.......
Q19. Derive the explicit formula from the given recursive formula:
an= 9.an-1, n>1
a1=11
Q20. Write recursive formula for the sequence:
57,46,35,24,13,…….
Answers:
A1. an= .an-1 ;
A2. 10th term=-85
11th term=-97
A3. an=
A4. A0=600000
An = An-1 (1.06)
, n
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A5. 31st term=-332
75th term=-816
A6. an= .an-1 ;
A7.
A8.
A9. an=
A10. an=
A11. recursive formula
an=an-1+11 ;
,n>1
Explicit formula
an=
A12. recursive formula
an=an-1+14 ;
,n>1
Explicit formula
an=
A13. T= 40
A14. an=9.(
A15. an=11.(
+45 where T is temperature of the coffee at any time t.
n-1
,n
n-1
and Sixth term=9/1024
,n
First four terms are 11,-22,44,-88
A16. an=21.(
n-1
,n
First three terms are
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A17. a1 =3
an= 3.an-1, n>1
A18. a1 =4
an= 5.an-1, n>1
A19. an= 11.9n-1, n
A20. an= an-1-11 , a1=57
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