Solution:
Given the expression below
[tex]3x^2-30x-72[/tex]Factorizing the expression gives
[tex]\begin{gathered} Factor\text{ out 3} \\ =3\left(x^2-10x-24\right) \\ =3(x^2-12x+2x-24) \\ =3(x(x-12)+2(x-12)) \\ =3\left(x+2\right)\left(x-12\right) \end{gathered}[/tex]Hence, the completely factored form of the quadratic expression is
[tex]3\left(x+2\right)\left(x-12\right)[/tex]