解方程

Answer all questions. You should use a calculator where appropriate.

You must show all necessary working clearly; no marks will be given for unsupported answers from a calculator.

Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place for angles in degrees, unless a different level of accuracy is specified in the question.

请回答所有题目。适当时应使用计算器。必须清楚展示所有必要的计算过程；仅给出计算器答案而没有过程，不予评分。除非题目另有精度要求，非精确数值答案保留 3 位有效数字，以度为单位的角度保留 1 位小数。

设 $u$ 为 $x$ 的实数立方根。原式化为二次方程，负的立方根也要保留。

Let $u=\sqrt[3]{x}$. Since $x^{2/3}=u^2$ and $(8x)^{1/3}=2u$, we have

Cubing $u=4$ and $u=-6$ gives $x=64$ and $x=-216$. Both satisfy the original equation.