Question 1051991
<pre><b>
{{{2-4(x+1)}}}{{{"">=""}}}{{{2(x-1)-18}}}

{{{2-4x-4}}}{{{"">=""}}}{{{2x-2-18}}}

{{{-4x-2}}}{{{"">=""}}}{{{2x-20}}}

Subtract 2x from both sides:

{{{-2x-2}}}{{{"">=""}}}{{{-20}}}

Add 2 to both sides:

{{{-2x}}}{{{"">=""}}}{{{-18}}}

Divide both sides by -2.  Since this is
dividing both sides by a negative number,
the inequality symbol must be reversed:

{{{x}}}{{{""<=""}}}{{{9}}}

Graph on a number line with a darkened circle
at 9 because it's {{{""<=""}}}, not {{{""<""}}}.

<=================================&#9787;------------------
-2 -1  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14

The interval notation is an abbreviation of the graph
on a number line. The darkened circle is denoted by "]"
and the rightmost point of the interval is 9, and the
interval goes to negative infinity on the left side, so 
the interval notation is

         {{{matrix(1,5,"(",-infinity,",",9,"]")}}}

Edwin</pre></b>