Question 1108339
The formula {{{f(x)=6x^2}}} can be used to find the surface area of a box, where {{{x}}} is the side length.
The domain is the set of {{{x}}} values where the function is defined.
As the surface area values mentioned are in square inches, thw {{{x}}} values would be plugged into the function as inches.
That justifies the choice not to include units in the steps to calculate the result.
The phrase "the surface area is greater than or equal to {{{24 in^2}}}, but less than or equal to {{{384 in^2}}}" translates as
{{{24<=6x^2<=384}}} .
We can multiply or divide all sides of an inequality by a positive number,
keeping the sihns the same way,
to get an equivalent inequality.
In this case,
{{{24/6<=6x^2/6<=384/6}}} --> {{{4<=x^2<=64}}} .
As {{{x}}} is a length in inches, it is a positive number,
so we can take square root of all sides of that inequality to find
{{{sqrt(4)<=sqrt(x^2)<=sqrt(64)}}} --> {{{2<=x<=8}}} .
The domain of the function is
{{{2<=x<=8}}} or {{{"[ 2 , 8 ]"}}} if we leave out the units,
or {{{2in<=x<=8in}}} or {{{"[ 2 in , 8 in ]"}}} if we want to include units.