![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
Method 1:
\Factor the each monomial.
\21x2y = 3 · 7 · x · x · y.
\63xy2 = 3 · 3 · 7 · x · y · y.
\The GCF is the product of the common prime factors in each monomial.
\GCF = 3 · 7 · x · y = 21xy.
\The greatest common factor of 21x2y and 63xy2 is 21xy.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
The greatest common factor of 21x2y and 63xy2 is 21xy.