Answer
$r=\left\{ -3,0,\dfrac{4}{5} \right\}$
Work Step by Step
Equating each factor to zero, then the solution to the given equation, $
2r(r+3)(5r-4)=0
$, is
\begin{array}{l}
2r=0
\\
r=\dfrac{0}{2}
\\
r=0
,\text{ OR}\\\\
r+3=0
\\
r=0-3
\\
r=-3
,\text{ OR}\\\\
5r-4=0
\\
5r=0+4
\\
5r=4
\\
r=\dfrac{4}{5}
\end{array}
Hence, $
r=\left\{ -3,0,\dfrac{4}{5} \right\}
$.
