Method 1:
\Factor the each monomial.
\16x = 2 · 2 · 2 · 2 · x
\36x = 2 · 2 · 3 · 3 · x
\The GCF is the product of the common prime factors in each monomial.
\GCF = 2 · 2 · x = 4x \ \
The greatest common factor of 16x and 36x is 4x.
The greatest common factor of 16x and 36x is 4x.