Question 81667
<pre><b>
multiply the fractions: 
{{{(2x^2-x-3)/(3x^2+7x+4)}}}.{{{(3x^2-11x-20)/(4x^2-9)}}}

Factor all the numerators and denominators:

{{{( (x+1)(2x-3) )/((x+1)(3x+4))}}}.{{{((x-5)(3x+4))/((2x-3)(2x+3)           )}}}

Indicate multiplication of numerators and denominators and write
them altogether as one fraction:

{{{( (x+1)(2x-3)(x-5)(3x+4) )/(  (x+1)(3x+4)(2x-3)(2x+3)) }}} 

The {{{(x+1)}}} in the top and bottom cancel.
The {{{(2x-3)}}} in the top and bottom cancel.
The {{{(3x+4)}}} in the top and bottom cancel.
All that's left is

{{{((x-5))/((2x+3))}}}

and you can erase the parentheses and just have

{{{(x-5)/(2x+3)}}}

Edwin</pre>