Answer
Choice D;
must use the Quadratic Formula
Work Step by Step
The discriminant of a quadratic equation $ax^2+bx+c=0,$ is given by $b^2-4ac$. Thus, the discriminant of the given equation, $
3m^2-10m+15=0
,$ is
\begin{align*}\require{cancel}
&
(-10)^2-4(3)(15)
\\&=
100-180
\\&=
-80
.\end{align*}
Since the discriminant is negative, then the equation $
3m^2-10m+15=0
$ has two nonreal complex numbers as solutions or $\text{
Choice D
}$.
Furthermore, since the discriminant is less than zero, then the given equation CANNOT be solved using the Zero-Factor Property. Hence, the Quadratic Formula must be used.