Answer
See below
Work Step by Step
Pick a point $(2,6)$
$y=a(x+3)(x+1)(x)\\
\rightarrow 6=a(2+3)(2+1)(2)\\ \rightarrow 6=30a\\\rightarrow a=\frac{1}{5}$
Hence, the equation will be $y=\frac{1}{5}x(x+3)(x+1)$
$y=a(x+3)(x+1)(x-1)\\
\rightarrow 6=a(2+3)(2+1)(2-1)\\ \rightarrow 6=15a\\\rightarrow a=\frac{2}{5}$
Hence, the equation will be $y=\frac{2}{5}(x+3)(x+1)(x-1)$