Question 393221
First I'll factor out {{{x}}}
{{{x*(x^2 + 3x - 40)}}}
I'll use the quadratic formula to factor the 2nd term
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
{{{a = 1}}}
{{{b = 3}}}
{{{c = -40}}}
{{{x = (-3 +- sqrt( 3^2-4*1*(-40) ))/(2*1) }}} 
{{{x = (-3 +- sqrt( 9 + 160 )) / 2 }}}
{{{x = (-3 +- sqrt( 169 )) / 2 }}}
{{{x = (-3 +13)/2
{{{x = 5}}}
and
{{{x = (-3 - 13)/2}}}
{{{x = -8}}}
From finding the roots, I can say
{{{x - 5 = 0}}} and
{{{x + 8 = 0}}}
The complete factorization is
{{{x*(x - 5)*(x + 8)}}}