SOLUTION: What's the common ratio of -5, 20, -80 i tried this An=A1*(r)^n-1

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Question 1070034: What's the common ratio of -5, 20, -80 i tried this An=A1*(r)^n-1


Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
This means, what is the common ratio between every pair of successive terms in your sequence.

system%2820%2F%28-5%29=r%2C+-80%2F20=r%29
The two values for r should be equal.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

What's the common ratio of -5, 20, -80 i tried this An=A1*(r)^n-1
You can use this formula: a%5Bn%5D+=+a%5B1%5Dr%5E%28n+-+1%29.

However, it's much easier to use the formula that states that: , which results in: 20%2F%28-+5%29+=+%28-+80%29%2F20%29 =====> - 4 = - 4

Thus, the common ratio or highlight_green%28matrix%281%2C3%2C+r%2C+%22=%22%2C+-+4%29%29