4 colour needed for this…i think
For this case we have the following polynomial:

We must find the greatest common factor of the terms of the polynomial.
The GCF of the coefficients is given by:

Then we look for the GFC of the variables:
We have then:

Finally rewriting we have:

Answer:
the complete factored form of the polynomial is:

Answer:
13: Skew
14: Parallel
16: Intersecting
17: Skew
18: No
19: Yes
20: No
21: Yes
Step-by-step explanation:
Skew is when 2 lines dont intersect, nor are parallel (On different planes)
Parallel is when 2 lines are on the same plane, and will never touch
Intersecting is when any set of given points go through each other