An arithmetic sequence has first term a = 5 and common difference d = 4. how many terms of this sequence must be added to get 4185?
Accepted Solution
A:
Given that in arithmetic sequence a=5 and common difference, d=4. Thus the number of terms of this sequence that must be added to attain 4185 will be found as follows: the explicit formula for arithmetic sequence is given by: sn=n/2(2a+(n-1)d) where n is the number of terms: thus plugging in the values we get: 4185=n/2(2*5+(n-1)4) solving for n we get: 8370=(10+4n-4) 8370=(6+4n) 4n=8364 n=8364/4 n=2091 thus the number of terms will be: 2091