Question 293646
<pre><font size = 4 color = "indigo"><b>
{{{15x+45x^2}}}

You took out only a numerical factor {{{15}}}, when you
should have factored out an {{{x}}} as well.  That is,
you should have factored out {{{15x}}}, not just {{{15}}} 

The complete factorization is:

{{{15x(x+3)}}}

What you did was not mathematically incorrect, it just was not
complete because the expression inside the parentheses, in
<font color = "red">red</font> below, can also be factored:

{{{15(red(x+3x^2))}}}

You can factor out an {{{red(x)}}} from inside the parentheses,
like this:

{{{15(red(x(x+3)))}}}

and then take away the black parentheses:

{{{15red(x(x+3))}}}

and so you end up with the right answer. But it's better 
to take out {{{15x}}} to begin with.  Then it's only
one step.

Edwin</pre>