Question 1069417
<pre>{{{matrix(1,7,
S[n],
"",
""="",
"",
30,
""-"",
10^""/3^(n-1))}}}

The sum of the first 5 terms is:

{{{matrix(1,14,
S[5],
"",
""="",
"",
30,
""-"",
10^""/3^(5-1),
"",
""="",
"",
10^""/3^4,
"",
""="",
10/81)}}}

To find the 5th term, we need to find the sum of the
first 4 terms and subtract from that value:

The sum of the first 4 terms is:

{{{matrix(1,14,
S[4],
"",
""="",
"",
30,
""-"",
10^""/3^(4-1),
"",
""="",
"",
10^""/3^3,
"",
""="",
10/27)}}}

So the 5th term is

{{{matrix(1,18,
10/81,
""-"",
10/27,
"",
""="",
"",
10/81,
""-"",
expr(10/27)*red(expr(3/3)),
"",
""="",
"",
10/81,
""-"",
30/81,
"",
""="",
-20/81)}}}

Edwin</pre>