Solve Infinite Series: Sum of -(5/4)^n

[NIZBIT]

[SOLVED] Infinite series help

Homework Statement

$$\sum- (\frac{5}{4})^n$$
i=infinity and n=0

Homework Equations

Convergence of a geometric series
$$\sum (ar)^n = a/(1-r) when 0<|r|<1$$

The Attempt at a Solution

I have to explain why this series diverges or converges. The test for divergence gives an answer of infinity so it diverges. The terms are 1, -5/4, 25/16, -125/64, 625/256... To me it looks like a geometric series with r=|-5/4| which diverges because |-5/4|$$\geq$$ 1. Is this correct?

 

[arildno]

Correct.

 

[NIZBIT]

thanks!