求满足不等式

的 $x$ 的取值集合，用 $a$ 表示，其中 $a$ 为正常数。

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。

两边非负，可以等价平方。整理并因式分解后，利用 $a>0$ 确定两个根的大小顺序。

Squaring both non-negative sides gives

Hence

Since $a>0$, the roots are ordered as $-5a/8<a/4$. The product is negative between them, so