SOLUTION: I can't tell which sequence I should be using in order to solve this equation... You need to find the 11th term. -10, 20, -40, 80

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Question 472774: I can't tell which sequence I should be using in order to solve this equation...
You need to find the 11th term.
-10, 20, -40, 80
Answer by Tatiana_Stebko(1326) About Me  (Show Source):
You can put this solution on YOUR website!
-10, 20, -40, 80 a geometric progression
a1=-10
r=a2%2Fa1=20%2F%28-10%29=-2
Formula an=a1%2Ar%5E%28n-1%29
the 11th term a11=a1%2Ar%5E%2811-1%29=-10%2A%28-2%29%5E10=-10%2A1024=-10240