Question 1176560
You could try factoring, or try applying Rational Roots Theorem, or attempt long division or synthetic division starting with {{{x+5}}} as divisor.

<pre>
-5  |   4   19   -8   -15
    |      -20    5   15
    |------------------------
        4   -1    -3


1   |   4   -1    -3
    |      4      3
    |_________________
        4   3     0--------------meaning, facto{{{4x+3}}}
</pre>
Roots are  -5, 1, and -3/4.

{{{f(x)=(x+5)(x-1)(4x+3)}}}






------------------This contains an early arithmetic mistake and is wrong-----------------
{{{(4x^3+19x^2-8x-15)/(x+5)}}}

<pre>
-5   |    4    19     -8    -15
     |
     |        -20     -5    115
     |__________________________________
         4      1    -23    100
</pre>

This means {{{f(x)=cross((x+5)(4x^2+x-23+100/(x+5)))}}} .