Question 1076321
<pre>
{{{matrix(1,9,7/2,",",  "_",",",  "_",",",  "_",",",  56/81)}}} 

{{{matrix(1,11,7/2,",",  expr(7/2)r,",",  expr(7/2)r^2,",",  expr(7/2)r^3,",",  expr(7/2)r^4,""="",56/81)}}}

{{{expr(7/2)r^4}}}{{{""=""}}}{{{56/81)}}}

Multiply both sides by {{{2/7}}}

{{{(2/7)expr(7/2)r^4}}}{{{""=""}}}{{{(2/7)expr(56/81)}}}

{{{r^4}}}{{{""=""}}}{{{16/81}}}

{{{r}}}{{{""=""}}}{{{"" +- root(4,16/81)}}}

{{{r}}}{{{""=""}}}{{{"" +- 2/3}}}

{{{matrix(1,9,7/2,",",  expr(7/2)("" +- 2/3),",",  expr(7/2)("" +- 2/3)^2,",",  expr(7/2)("" +- 2/3)^3,",",56/81)}}}

{{{matrix(1,9,7/2,",",  "" +- 7/3,",",  expr(7/2)(4/9),",",  expr(7/2)("" +- 8/27),",",56/81)}}}

{{{matrix(1,9,7/2,",",  "" +- 7/3,",",  14/9,",", "" +- 28/27,",",56/81)}}}

Edwin</pre>