Question 1157838
given a term in a geometric sequence and the common ratio find the term named in the problem and the explicit formula
http://prntscr.com/s9icar
<pre>Term of a G.P. formula: {{{matrix(1,3, a[n], "=", a[1]r^(n - 1))}}}
{{{matrix(1,3, a[6], "=", a[1](- 2)^(6 - 1))}}} ----- Substituting 6 for n, and - 2 for r
{{{matrix(1,3, - 128, "=", a[1](- 2)^5)}}} ------ Substituting {{{matrix(1,3, -  128, for, a[n])}}}
{{{matrix(1,3, - 128, "=", a[1](- 32))}}}
{{{matrix(1,3, (- 128)/(- 32), "=", a[1])}}}
{{{matrix(1,3, 4, "=", a[1])}}} 
For the value of {{{a[11]}}}, or the 11th term, substitute {{{matrix(3,3, 11, for, n, 4, for,  a[1], - 2, for, r)}}} into the G.P. formula: {{{matrix(1,3, a[n], "=", a[1]r^(n - 1))}}}, and SIMPLIFY.