SOLUTION: Find the number of terms in the series and then find the sum. Evaluate the sum. 12 + 14 + 16 + 18 + 20 + ... + 38

Algebra ->  Sequences-and-series -> SOLUTION: Find the number of terms in the series and then find the sum. Evaluate the sum. 12 + 14 + 16 + 18 + 20 + ... + 38      Log On


   

Question 455531: Find the number of terms in the series and then find the sum. Evaluate the sum.
12 + 14 + 16 + 18 + 20 + ... + 38
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

first term, a=12
number of terms, n=14
difference between any two adjacent terms, d=2
last term, L=+a%2B%28n-1%29d=12%2B%2814-1%292=12%2B26=38+

sum=+n%28a%2BL%29%2F2+ which is

sum=+14%2812%2B38%29%2F2+

sum=+14%2850%29%2F2+
sum=+7%2850%29+
sum=+350+