For this case we must find the inverse of the following function:

We follow the steps below:
Replace f(x) with y:

We exchange the variables:

We solve for "y":

Multiply by -2 on both sides of the equation:

We raise both sides of the equation to the square to eliminate the radical:

We subtract 3 from both sides of the equation:

We change y by f ^ {- 1} (x):

Answer:
In euros Derek has twenty two dollars and eighty cents
What we know:
3.14 pi
radius: 7in.
Result units: in^3, this is the results of in used for radius; no conversion needed
Formula volume of a sphere: (4/3)* pi * r^3
(4/3)(3.14)(7)(7)(7)
(4/3)(3.14)(343)
(4/3)(1077.02)
(1.3)(1077.02) \\repeated 3 infinite
1436.026666\\repeated 6inf
The volume of the sphere is about 1436.0266 in^3