Question

Why does the addition sign change in 9^-(n+2) when you convert it to 1/9^(n-2)?

Answer 1

there is now change

\[9^{-(n +2)} = \frac{1}{9^{n + 2}}\]

for a proof

\[\frac{1}{9^n} \times \frac{1}{9^2} = \frac{1}{9^{(n + 2)}} = 9^{-(n + 2)}\]

Answer 2

so what is happening in this step? http://tutorial.math.lamar.edu/Classes/CalcII/Series_Special_files/eq0020MP.gif

Answer 3

oh. wait i think i get it. nvm