You can use the formula $A=\frac{{\mathrm{\pi d}}^2}{4}$ to find the area ($A$) of a circle, where $d$ is the diameter of the circle.

Express the formula $A=\frac{{\mathrm{\pi d}}^2}{4}$ in a way that would allow you to find the diameter of the circle when the area is known.

If $f\left(x\right)=3x-1$ and $f\left(x\right)=3$, find $x$.

If $g\left(x\right)=\sqrt{4x+1}$ and $g\left(x\right)=5$, find the value of $x$.

For the following pair of functions, evaluate $fg\left(x\right) \& gf\left(x\right)$.

$f\left(x\right)=x+6$

$g\left(x\right)=x-3$

For the following pair of functions, evaluate $fg\left(x\right) \& gf\left(x\right)$.

$f\left(x\right)=2x^2-3x+1$

$g\left(x\right)=5x$

For the following pair of functions, evaluate $fg\left(x\right) \& gf\left(x\right)$.

$f\left(x\right)=3x^2-4x+2$

$g\left(x\right)=3x-2$

For the following pair of functions, evaluate $fg\left(x\right) \& gf\left(x\right)$.

$f\left(x\right)=\frac{4x}{3}$

$g\left(x\right)=x^2-9$

Given $f\left(x\right)=2x \& g\left(x\right)=-x$ find $fg\left(x\right)$.