Answer
a) $3x^{2}$
a) $4y$
a) $ab^{2}$
Work Step by Step
a) The GCF is $3\times x^{2} = 3x^{2} $
$6x^{2} = 2\times 3\times x^{2}$
$9x^{4} = 3\times 3\times x^{4}$
$-12x^{5} = -1\times 2\times 2\times 3\times x^{5}$
b) The GCF is $2\times 2\times y = 4y$
$-16y = -2\times 2\times 2\times 2\times y$
$-20y^{6} = -2\times 2\times 5\times y^{6}$
$40y^{4} = 2\times 2\times 2\times 5\times y^{4}$
c) The GCF of $a^{5}, a, a^{3}$ is $a$.
The GCF of $b^{4}, b^{3}, b^{2}$ is $b^{2}$.
Hence the GCF of $a^{5}b^{4}, ab^{3}, a^{3}b^{2}$ is $ab^{2}$.