Use summation notation.. pleas help?
2 Answers
B:
Explanation:
If I understand you right, you want to know which of A, B, C, and D would give the seriues in question.
First we note that
Therefore A and D can be eliminated, since the first term is
We can also eliminate C, since
That leaves B, since (-2)^(n-1) will alternate between positive values for (n-1) being even (n-1=0, n-1=2 etc.) and negative for n-1 being odd (n-1=1, n-1=3 etc)
B
Explanation:
If you put n=1 into each answer:
A gives
B gives
C gives
D gives
So you can cancel out A and D
If you put n=2 into
B gives
C gives
You can see B gives the first two numbers in the sequence