Fan & medal for help?:)

What is the sum of the geometric sequence 1, -6, 36,...if there are 6 terms?

A)-39,991
B)6,665
C)-6,665
D)39,991

Question

Fan & medal for help?:)

What is the sum of the geometric sequence 1, -6, 36,...if there are 6 terms?

A)-39,991
B)6,665
C)-6,665
D)39,991

yowarning · Answer

well find that you times 1 by to get  -6

mathmale · Answer

there is a formula for the sum of an infinite geometric sequence.  There's also a formula for the nth sum of a geometric sequence.  Please look through your learning materials for the 2nd one.

Type it out here.  Then we can apply it to the quesiton at hand.

mathmale · Answer

Write out the first six terms of this sequence:  1, -6, 36,..

Then add these 6 terms together.

mathmale · Answer

I still think you should look for the formula for the nth term of a geometric sequence.  Do the same problem now using that formula.  Your answers should be the same.