Pre-Calculus problem..function? Help please!?

Question

We have a large worksheet to do, and this is the only problem I cannot firgure out. Does anybody have any help you could provide, so I can solve this?

A rectangle has an area of 25m^2. Express the perimeter of the rectangle as a function of the length of one of its sides.

Thanks in advance

Answer 1

S = a*b

25 = a*b

b = 25/a

p = 2(a + b)

p = 2(a + 25/a)

p = 2a + 50/a

p = (2a^2 + 50) / a

Answer 2

L*W =25

W = 25/L

P = 2L + 2W = 2L + 50/L