The sequence 5, 9, 13 is an arithmetic sequence with a common difference of 4. To find the 18th term, we can use the formula for the nth term of an arithmetic sequence:
an = a1 + (n-1)d
Where:
an = 18th term
a1 = 1st term = 5
d = common difference = 4
a18 = 5 + (18-1)4
a18 = 5 + 17*4
a18 = 5 + 68
a18 = 73
Given that the 18th term is 92, we have:
92 = a18
Now, we can find the sum of the first 18 terms of the sequence using the formula for the sum of an arithmetic series:
Sn = (n/2)(a1 + an)
Where:
Sn = sum of the first n terms
n = number of terms = 18
a1 = 1st term = 5
an = 18th term = 92
S18 = (18/2)(5 + 92)
S18 = 9(97)
S18 = 873
Therefore, the sum of the first 18 terms of the sequence is 873.
In sequence 5,9,13 find the sum of the first 18th term given that the 18th term is 92
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