Problem

甲、填充題：共 8 題，每題 8 分，共 64 分。請將答案依題號順序寫在答案卷上。

8. Suppose the demand functions of two commodities are $x=f(p,q)=\dfrac{q}{1+\sqrt p}$ and $y=g(p,q)=\dfrac{3p}{1+q^4}$. Determine whether these two commodities are substitute, complementary, or neither. Answer : \underline{\quad(1)\quad}