Method 1:
\Factor the each monomial.
\14n = 2 · 7 · n
\42n3 = 2 · 3 · 7 · n · n · n
\The GCF is the product of the common prime factors in each monomial.
\GCF = 2 · 7 · n = 14n \ \ The greatest common factor of 14n and 42n3 is 14n.
\The greatest common factor of 14n and 42n3 is 14n.
\