Question 1117946
{{{12x^3+x^2-20x}}}


{{{x(12x^2+x-20)}}}


Look at all the combinations for the quadratic factor that you can make and see which one works.


<pre>
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(12x  1)(x  20)
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(12x 2)(x  10)
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(12x  20)(x  1)
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(12x  10)(x  2)
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(12x 4)(x  5)
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(12  5)(x  4)
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..
.
still many more combinations to look at...
</pre>

If you try general solution formula for a quadratic expression (to find roots), then you would start with 
{{{x=(-1+- sqrt(1+4*12*20))/24}}}

Showing roots to be  {{{system(-4/3,and,5/4)}}}.


With some integer factor k, your quadratic factor would be  
{{{k(x+4/3)(x-5/4)}}}
which you should be able to work with and finish.