SOLUTION: whats the sum of the first 50 terms 204+198+192+186

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Question 1100401: whats the sum of the first 50 terms 204+198+192+186
Found 2 solutions by Fombitz, ikleyn:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
The difference between terms is -6.
d=-6
.
.
a%5B1%5D=204
.
.
The sum of a arithmetic progression is,
S%5Bn%5D=%28n%2F2%29%282a%5B1%5D%2B%28n-1%29d%29
So,
S%5B50%5D=%2850%2F2%29%282%28204%29%2B%2850-1%29%28-6%29%29
S%5B50%5D=25%28408-49%286%29%29
S%5B50%5D=25%28114%29
S%5B50%5D=2850

Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
.
There is a bunch of introductory lessons on arithmetic progressions in this site:
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
    - Word problems on arithmetic progressions


They are written  SPECIALLY  for you . . .

Why do not you read it ??

You will be able,  like a magician,  sum up any arithmetic progression . . .