Answer:
2,322,775
Explanation:
Given a1 = 4 and ai =ai-1 +11
when i = 2
a2 = a2-1+11
a2 = a1+11
a2 = 4+11
a2 = 15
when i = 3
a3 = a2+11
a3 = 15+11
a3 = 26
The sequence formed by a1, a2, a3... is am arithmetic sequence as shown;
4, 15, 26...
Sum of nth term of an arithmetic sequence = n/2{2a+(n-1)d}
a is the first term = 4
d is the common difference = 15-4 = 26-15 = 11
n is the number of terms.
Since we are to find the sum of the first 650 terms in the sequence, n = 650
S650 = 650/2{2(4)+(650-1)11}
S650 = 325{8+(649)11}
S650 = 325(8+7,139)
S650 = 325×7147
S650 = 2,322,775