Hi there! The greatest common factor/divisor (gcf / gcd) is 2x.
We can see this by writing the numbers as multipliers:
[tex]14 {x}^{2} = 7 \times 2 \times x \times x[/tex]
[tex]4xy = 2 \times 2 \times x \times y[/tex]
Now we can see that the factors which are in common are 2 and x. Therefore the greatest common factor/divisor (gcf / gcd) of the two numbers is 2x.