题目
Solve the equation , giving your answer in an exact form.
题目中文翻译
解方程 ,答案用精确形式表示。
原卷通用作答要求
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。
解答
解法一
思路
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先检查对数的定义域,再用对数法则合并右侧。解出的负根会违反 的定义域。
答题过程
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The logarithms require and , hence .
Using logarithm laws,
Therefore
The negative root is outside the domain, while satisfies it. Hence .