Final answer:
To find the option that does not have a Greatest Common Factor (GCF) of 3x^2, we need to factor out 3x^2 from each option and see which one can't be factored. Option D, 3x + 21x^3, does not have a GCF of 3x^2.
Step-by-step explanation:
Let's find the GCF of each option and see which one does not have a GCF of 3x^2.
A. 6x^3 - 3x^2
We can factor out 3x^2 from both terms: 3x^2(2x - 1). So the GCF is 3x^2, option A has a GCF of 3x^2.
B. 3x^5 + 18x^2
We can factor out 3x^2 from both terms: 3x^2(x^3 + 6). So the GCF is 3x^2, option B has a GCF of 3x^2.
C. 3(x^2 + 5x^3)
We can factor out 3x^2 from both terms: 3x^2(1 + 5x). So the GCF is 3x^2, option C has a GCF of 3x^2.
D. 3x + 21x^3
We can't factor out 3x^2 from both terms, so option D does not have a GCF of 3x^2.
Therefore, the correct answer is D. 3x + 21x^3.