Question

The volume of water and a rectangle swimming pool can be modeled by the function v(x)=x^3+13x-210. If the depth of the pool is given by the expression x-3, what are the expressions that represent the width and length of the pool?

Answer 1

Answer:

Required,

$L=\frac{3+\sqrt{37}}{2}-\frac{144}{x-3}$

$W=\frac{3-\sqrt{37}}{2}-\frac{144}{x-3}$

Step-by-step explanation:

Given volume and depth respectively,

$V(x)=x^3+13x-210$ and $x-3$

To find length and width of the rectanglular swiming pool we know,

Volume=length$\times$height$\times$depth.

Let depth=D=x-3, length=L, width=W, then

$V=DLW$

$x^3+13x-210= LW(x-3)$

$LW=\frac{x^3+13x-210}{x-3}$

After divide we will get $x^2-3x-22$ with remainder -144.

Thus,

$x^3+13x-210=(x^2-3x-22)(x-3)-144=(x-3)LW$

Now to find root of,

$x^2-3x-144=\frac{3\pm\sqrt{9+88}}{2}=\frac{3\pm \sqrt{37}}{2}$

Thus,

$L=\frac{3+\sqrt{37}}{2}-\frac{144}{x-3}$

$W=\frac{3-\sqrt{37}}{2}-\frac{144}{x-3}$