SOLUTION: Find the 15th term of the given sequence -9, 27 , -81.....

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Question 607190: Find the 15th term of the given sequence -9, 27 , -81.....
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

first, identify the first term in the sequence, call this number a.
you have a=-9
second, calculate the common ratio r of the sequence
in your case the common ratio r is -3
if you multiply first term -9 by common ratio -3 you get second term 27
third, you need n, the term you need to find
in your case n=15

forth, insert these values into the equation:
ar%5E%28n-1%29 and calculate the 15th term
-9%28-3%29%5E%2815-1%29=-9%2A%28-3%29%5E14=-9%2A4782969=-43046721
so, your sequence is:
-9, 27 , -81, 243, -729, 2187,-6561, 19683, -59049, 177147,-531441,1594323,-4782969, 14348907, -43046721