We write the factorization of the terms just like if they were numbers:
[tex]33x^3 = 3^1 11^1 x^3[/tex]
[tex]18x^6 = 2^1 3^2 x^6[/tex]
We take the minimum for each exponent:
[tex]\textrm{GCF} = 2^0 3^1 11 ^0 x^3[/tex]
[tex]\textrm{GCF} = 3x^3[/tex]
Choice C
