Answer:
492,800
Step-by-step explanation:
Given ith term of an arithmetic sequence as shown:
ai = a(i-1)+2
and a1 = 5
When i = 2
a2 = a(2-1)+2
a2 = a1+2
a2 = 5+2
a2 = 7
When i = 3
a3 = a(3-1)+2
a3 = a2+2
a3 = 7+2
a3 = 9
It can be seen that a1, a2 and a3 forms an arithmetic progression
5,7,9...
Given first term a1 = 5
Common difference d = 7-5= 9-7 = 2
To calculate the sum of the first 700 of the sequence, we will use the formula for finding the sum of an arithmetic sequence.
Sn = n/2{2a1+(n-1)d}
Given n = 700
S700 = 700/2{2(5)+(700-1)2}
S700 = 350{10+699(2)}
S700 = 350{10+1398}
S700 = 350×1408
S700 = 492,800
Therefore, the sum of the first 700 terms in the sequence is 492,800
