Express the perimeter P of a square as a function of the area.

We need write the area of a square as a function of the
perimeter.

Let us write the equation of the
perimeter.

Let the side of a square be
x.

Then the perimeter P =
4x.

==> x = P/4

Now we
will write the equation of the area.

==> A =
x^2

Now we will substitute with
(1).

==> A = (P/4)^2 = p^2
/16

==> A(p) = p^2/
16.