Question

Factor out the GCF: 21c^9−28c^6

Select one:
a. 7c^3(3c^6−4c^3)
b. 7c^6(3c^3−4)
c. 7c(3c^8−4c^5)
d. 7(3c^9−4c^6)

Answer 1

To factor you find out what is common. 7 can go into both. Also c^6, so bring those outside:

7c^6(???-???)

Now to find what goes in, simply remove 7c^6 from both 21c^9 and - 28c^6, which would be:

7c^6(3c^3−4) so Option B).