This looks like an odd problem.
Just start with a simple expression with 7 as a factor, and then multiply it out.
For example:
7(x+1)(x+2)
Here 7 could be the GCF.
Now multiply it out:
7(x^2+3x+2) =
7x^2+21x+14
So our factorable polynomial is 7x^2+21x+14
And its two equivalent forms are:
7(x^2+3x+2)
and
7(x+1)(x+2)