[tex]\begin{cases} x = -4\implies &x+4=0\\ x=-5\implies &x+5=0\\ x = 0\implies &x=0\\ x=\frac{1}{3}\implies &x -\frac{1}{3}=0\\ &3\left( x -\frac{1}{3} \right)=3(0)\\ &3x-1=0 \end{cases} \\\\[-0.35em] ~\dotfill\\\\ (x+4)(x+5)(x)(3x-1)=\stackrel{\textit{original equation}}{0} \\\\\\ (x^2+9x+20)(x)(3x-1)=y\implies (x^3+9x^2+20x)(3x-1)=y \\\\\\ (3x^4+27x^3+60x^2)+(-x^3-9x^2-20x)=y[/tex]
[tex]3x^4+27x^3+60x^2-x^3-9x^2-20x=y \\\\[-0.35em] ~\dotfill\\\\ ~\hfill 3x^4+26x^3+51x^2-20x=y~\hfill[/tex]
