a)\(3x^2-5x-2=3x^2-6x+x-2=3x\left(x-2\right)+\left(x-2\right)\)
\(=\left(3x+1\right)\left(x-2\right)\)
\(x^3-9x^2+14x=x\left(x^2-9x+14\right)\)
\(=x\left(x^2-2x-7x+14\right)=x\left(x\left(x-2\right)-7\left(x-2\right)\right)\)
\(=x\left(x-7\right)\left(x-2\right)\)