\(a,3x+5\sqrt{x}-2\\ =3x+6\sqrt{x}-\sqrt{x}-2\\ =3\sqrt{x}\left(\sqrt{x}+2\right)-\left(\sqrt{x}+2\right)\\ =\left(3\sqrt{x}-1\right)\left(\sqrt{x}+2\right)\\ b,16-x^2\\ =4^2-x^2\\ =\left(4-x\right)\left(4+x\right)\\ c,x^2+\sqrt{x}\\ =\sqrt{x^4}+\sqrt{x}\\ =\sqrt{x}\left(\sqrt{x^3}+1^3\right)\\ =\sqrt{x}\left(\sqrt{x}+1\right)\left(x-\sqrt{x}+1\right)\)