SOLUTION: How many terms

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Question 909056: How
many
terms

Found 2 solutions by MathLover1, richwmiller:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
How many terms of the arithmetic sequence
-3,2,7,...
must be added together the sum of the series to be 116?
What is the equation for this arithmetic sequence?
Explain your process.

arithmetic sequence has a common difference d
the recursive formula for an arithmetic sequence is written in the form a%5Bn%5D=a%5Bn-1%5D%2Bd
Rather than write a recursive formula, we can write an explicit formula. The explicit formula is also sometimes called the closed form. To write the explicit or closed form of an arithmetic sequence, we use
a%5Bn%5D=a%5B1%5D%2B%28n-1%29d
in this case -3,2,7,.... d=5
check:
-3%2B5=2
2%2B5=7
so, next one is 7%2B5=12
-3 ,2, 7 ,12,17,22,27,32,37,42....
How many terms must be added together the sum of the series to be 116, we can find out by adding
++-3%2B2%2B7%2B12%2B17%2B22%2B27%2B32=116
so, the answer is: we need first 8 terms



Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Do it right!