Answer :
[tex]\begin{gathered} \text{ 5x}^3-3x^2\text{ - 15x + 9} \\ \text{ x}^2(5x\text{ - 3) - 3(5x - 3)} \\ (5x-3)(x^2\text{ - 3)} \end{gathered}[/tex]
Just look for the common terms of the first two terms, and th common factors of the others two terms.
