Hi there!
The answer is:
[tex]6p {}^{3} - 12 {p}^{2} + 9p = 3p(2 {p}^{2} - 4p + 3)[/tex]
We can find this answer by writing the factors.
[tex]6 {p}^{3} = 3 \times 2 \times p \times p\times p[/tex]
[tex] - 12 {p}^{2} = 3 \times - 4 \times p \times p[/tex]
[tex]9p = 3 \times 3 \times p[/tex]
Now we can see that the terms that are in common are 3 and p. Therefore, the GCF is 3p.