\(f_{1}(x)=\sqrt{x^2(4-x^2)}\)

\(f_{2}(x)=x\sqrt{4-x^2}\)

\(f_{3}(x)=x^2\sqrt{4-x^2}\)

\(f_{4}(x)=\sqrt{x^4(4-x^2)}\)

\(f_{5}(x)=\Large\frac{\sqrt{4-x^2}}{x}\)

\(f_{6}(x)=\sqrt{\Large\frac{4-x^2}{x^2}}\)

\(f_{7}(x)=\Large\frac{\sqrt{4-x^2}}{x^2}\)

\(f_{8}(x)=\sqrt{\Large\frac{4-x^2}{x^4}}\)