What is the missing factor

(8x^3)(e^x) + (24e^x)(x^2) = (8e^x)(x^2)( )

any ideas?

Rearranged a bit you can get:
x(x^2)(8e^x) + 3(8e^x)(x^2)

Factor out (8e^x)(x^2)
You get
(8e^x)(x^2)(x+3)