The greatest common factor or GCF is the largest factor that all terms have in common.

The terms of '4 + 7y^3' are '4' and '7y^3'

GCF(4, 7y^3) = 1

Click here to see the solution.

Not all polynomials can be factored.

Just like some numbers are prime, some polynomials are prime, so in your case the polynomial cannot be factored.