Method 1:
\Factor the each monomial.
\40x2 = 2 · 2 · 2 · 5 · x · x
\16x = 2 · 2 · 2 · 2 · x
\The GCF is the product of the common prime factors in each monomial.
\GCF = 2 · 2 · 2 · x = 8x
\ The greatest common factor of 40x2 and 16x is 8x.
The greatest common factor of 40x2 and 16x is 8x.