If 120 feet of fence is to be used to enclose a rectangular yard, then the resulting area of the fenced yard is given by A = x(60-x)
where x is the width of the rectangle,
(a) If A = A(x), find A(3) and A(50).
A(3) = __________ ft²
A(50) =__________ ft2
(b) What restrictions must be placed on x (the domain) so that the problem makes physical sense? (Enter your answer using interval notation.)