Find nth term and 15th term of an arithmetic sequence 3,8,13,18
Answers
Answered by
2
Answer:
tn = a+(n-1)×d
t15 = 3+(n-1)×5
=3+(5n-5)
3+5n-2
t15 = 5n-1
t15 =5×15-1
75-1
t15 = 74
Answered by
8
Given :
- A.P. 3,8,13,18.....
To find :
- the 15th term
Solution :
The given sequence is in A.P.
its first term a 3
d = 8 - 3
d = 5
t15 = ?
tn = a + (n -1)d
t15 = a + (15 - 1) d
t15 = 3 + 14 × 5
t15 = 3 + 70
t15 = 73
∴ 15th term is 73
Extra formula's :
- t_n = a + ( n - 1 ) d
- S_n = n/2 [ 2a + ( n - 1 ) d ]
- S_n = n/2 ( a + 1 )
Similar questions