The surface area S of a single-celled organism may be found by multiplying 4π times the square of the radius r of the cell. Express S as a function of r.

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Step-by-step explanation:

It is given that, the surface area S of a single-celled organism may be found by multiplying 4π times the square of the radius r of the cell.  

We need to express S as a function of r.

Let r be the radius of the cell and S(r) be the surface area of single-celled organism when radius is r.

According to the question,

Therefore, the required function is .