Question 481815
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi,
geometric sequence: {4,-12,36,-108,...}  r = -3
{{{a[n]=a[1]r^(n-1)}}}
{{{s[n]=a1*(1-r^n)/(1-r)}}}   
{{{s[11]=4*(1-(-3)^11)/(4)= highlight(177148)}}}