Question 303394
{{{35+70+140+280+"..."+S[7]}}}
<pre><font size = 4 color="indigo"><b>
It's geometric with r=2 because each term is 2 times the
preceding term:

{{{S[n]=a[1]r^(n-1)}}}

{{{n=7}}}, {{{a[1]=35}}},  {{{r=2}}}

{{{S[7]=35(2)^(7-1)}}}

{{{S[7]=35(2)^6}}}

{{{S[7]=35(64)}}}

{{{S[7]=2240}}}

Edwin</pre>