Question 930752: Hi would you please help me with this homework.
Write a formula for the nth of the following geometric sequence.
-3,3/4,-3/16,3/64...
According to my professor the answer is an=-3*(-1/4)^n-1
Would you please show me the steps on how to solve this problem. Thank you
Found 3 solutions by jim_thompson5910, josgarithmetic, MathLover1:
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! The first term is -3. So a = -3
The common ratio is -1/4. This is because you multiply each term by -1/4 to get the next term.
You can see this if you divide the second term (3/4) by the first term (-3) and you'll get -1/4. You could also divide the third term by the 2nd term, or the 4th over the 3rd, etc etc
So r = -1/4
-------------------------------------------------------
We now know
a = -3
r = -1/4
You plug them into the general geometric sequence formula
an = a*(r)^(n-1)
to get
an = -3*(-1/4)^(n-1)
------------------------------------------------------------------------------------------------------------------------
If you need more one-on-one help, email me at jim_thompson5910@hotmail.com. You can ask me a few more questions for free, but afterwards, I would charge you ($2 a problem to have steps shown or $1 a problem for answer only).
Alternatively, please consider visiting my website: http://www.freewebs.com/jimthompson5910/home.html and making a donation. Any amount is greatly appreciated as it helps me a lot. This donation is to support free tutoring. Thank you.
Jim
------------------------------------------------------------------------------------------------------------------------
Answer by josgarithmetic(39618) (Show Source):
You can put this solution on YOUR website! You should check each successive pair of terms for a common ratio. You will find it to be  , forming the same general term expected.
Answer by MathLover1(20850)  (Show Source):
|
|
|
