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Val97
Please Help! Show me how its done please! Find the sum of the first 8 terms of the sequence. 1, -3, -7, -11, ...
sooo, you need help adding? or is it that you really need help in determining all the 8 terms?
since the numbers are getting smaller, or going negative, ... and they seem fairly close together. We can try to see if they are subtracting a like amount each time.
Fine out what the term is going up by. I see -4
I need help determining all the 8 terms, this is pre cal and it really confuses me. I'm not sure what formula to use. The Arithmetic Sequence formula?
formulas are only half the battle. seeing a pattern is the key once you see that pattern, the formula is known by default
So that is it? Its isn't any of the formulas they gave me?
if you subtract 4 from the last term given, what do you get?
.... or if you want to create an expression to use in summation thats fine too \[\sum_{n=a}^b~a_1+d(n-1)\] \[\sum_{n=a}^b~a_1+\sum_{n=a}^bd(n-1)\] \[a_1(b-a)+d\sum_{n=a}^bn-1\] \[a_1(b-a)+d\sum_{n=a}^bn-d\sum_{n=a}^b1\] \[a_1(b-a)+d\sum_{n=a}^bn-d(b-a)\] stuff like that
but yes ..., -15, -19, -23, -27 fill in all 8 terms
\[\frac{n}{2}(a_1+a_8)=sum\]
youre welcome, good luck :)