Let me write the polynomial in the usual order (decreasing powers), just for a matter of habit:
[tex] 6s^6+18s^4-9s^3 [/tex]
As for the numeric part, we can factor a 3, because it's the largest common divisor of 6, 9 and 18:
[tex] 6s^6+18s^4-9s^3 = 3(2s^6+6s^4-3s^3)[/tex]
For the variable part, we can factor a [tex] s^3 [/tex], because it's the power with the smaller exponent appearing in all terms:
[tex] 3(2s^6+6s^4-3s^3) = 3s^3(2s^3+6s-3)[/tex]
