题目
In the diagram, the graph with equation is shown with solid lines and the graph with equation is shown with broken lines.
(a) Describe fully a sequence of transformations which transforms the graph of to the graph of . You should make clear the order in which the transformations are applied.
(b) Find an expression for in the form , where , and are constants.
题目中文翻译
图中,方程为 的图像用实线表示,方程为 的图像用虚线表示。
(a) 完整描述一组将 的图像变为 的图像的变换,并清楚说明这些变换的先后顺序。
(b) 求 的表达式,写成 的形式,其中 、 和 为常数。
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
(a)
解法一
思路
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对应点都右移 。实线的高度差 变成虚线的高度差 ,所以纵坐标先缩为一半,再补足整体高度。
答题过程
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The points and map to and . First stretch by scale factor in the -direction, then translate by . This sends to .
解法二
思路
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若先平移,纵向位移也会缩为一半,因此先上移 。
答题过程
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First translate by , then stretch by scale factor in the -direction. The resulting point is , which gives the required image.
(b)
解法一
思路
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新横坐标是原横坐标加 ,所以要用 查回原高度。
答题过程
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At a new coordinate , the old height is . Applying the vertical scale and shift gives
Thus , and .