Are the following functions odd?
f : x\longmapsto \dfrac{2x}{3-x^2}
f : x\longmapsto x^4 - x^3 + 7
f : x\longmapsto \dfrac{\sqrt{x^4 - x^2}}{x}
f : x\longmapsto \dfrac{\sqrt[3]{x}}{x^4}
f : x\longmapsto \dfrac{\sqrt[3]{x}}{x^5}
f : x\longmapsto \dfrac{x^2 + 4}{x^3 - x}
f : x\longmapsto x^5 + 4x^3 - x