Answer
$$(x+4)(3x-2) $$
Work Step by Step
First, for the polynomial $3x^2 + 10x - 8$, we write
$$ 3x^2 + 10x - 8=3x^2 +12x -2x-8 .$$ By grouping the first two terms and the second two terms and then taking common factors, we have $$3x^2 +12x -2x-8 =3x(x+4)-2(x+4)=(x+4)(3x-2) .$$