Answer
$3x^{2}(2\pi-3)$
Work Step by Step
$ A_{1}=\pi r^{2}\qquad$...area of a circle
$ A_{1}=\pi(6x)^{2}\qquad$...substitute 6x for r.
$A_{1}=6\pi x^{2}\qquad...$simplify.
$A_{2}=s^{2}\qquad...$area of a square.
$A_{2}=(3x)^{2}\qquad...$substitute 3x for s.
$A_{2}=9x^{2}\qquad...$simplify.
The area of the yellow part of the tabletop is $A_{1}-A_{2}$, or $6\pi x^{2}-9x^{2}$.
$6\pi x^{2}-9x^{2}\qquad...$find the GCF.
$6\pi x^{2}=2\cdot(3)\cdot\pi\cdot(x\cdot x)$
$-9x^{2}=-1\cdot(3)\cdot 3\cdot(x\cdot x)$
GCF=$(3)\cdot(x\cdot x)$, or $3x^{2}$.
$6\pi x^{2}-9x^{2}\qquad...$factor out the GCF
$=3x^{2}(2\pi)-3x^{2}(3)\qquad...$apply the Distributive Property.
$=3x^{2}(2\pi-3)$
The factored form of the area of the yellow part of the tabletop is $3x^{2}(2\pi-3)$.
