Posted by COFFEE on .
infinity of the summation n=0: ((n+2)/(10^n))*((x5)^n)
.. my work so far. i used the ratio test
= lim (n>infinity)  [((n+3)/(10^(n+1)))*((x5)^(n+1))] / [((n+2)/(10^n))*((x5)^n)] 
.. now my question is: was it ok for me to add "+1" to "n+2" to become "n+3"?
= lim (n>infinity)  [((n+3)/(10^(n+1)))*(((x5)^(n+1))/1)] * [((10^n)/(n+2))*(1/((x5)^n))] 
= lim (n>infinity)  [(((n+3)(x5))/10)*(1/(n+2))] 
how do i finish this so that i could find the endpoints? please help. thank you.

polser elmetary 
roger,
what is the answer x5/3=10