Difficulty: Easy
Correct Answer: (1, -4)
Explanation:
Introduction / Context:This coordinate geometry question checks your understanding of reflections in the Cartesian plane. When a point is reflected in the x axis, its horizontal position remains unchanged, while its vertical coordinate changes sign. Knowing this rule allows you to find the new coordinates quickly without complex calculations.
Given Data / Assumptions:
Concept / Approach:The rule for reflection in the x axis is simple: a point (x, y) becomes (x, -y). The x coordinate stays the same because reflection occurs vertically across the horizontal axis. The y coordinate changes sign because the point is mirrored to the opposite side of the axis. Applying this rule directly gives the image of the original point.
Step-by-Step Solution:
Step 1: Identify the original coordinates: x = 1 and y = 4. Step 2: Apply the reflection rule in the x axis: (x, y) → (x, -y). Step 3: Keep x the same: x = 1. Step 4: Change the sign of y: y = 4 becomes -4. Step 5: Therefore, the reflected point is (1, -4).Verification / Alternative check:You can visualize the Cartesian plane: the x axis is horizontal. The point (1, 4) is one unit to the right of the origin and four units above the x axis. Reflecting it in the x axis puts it one unit to the right of the origin but four units below the x axis, which corresponds to (1, -4). This simple mental picture confirms the calculation.
Why Other Options Are Wrong:
(1, 4): is the original point, not its reflection. (-1, 4): reflects in the y axis, not in the x axis. (-1, -4): reflects in both axes (origin reflection). (4, 1): swaps coordinates and does not correspond to any standard axis reflection for this point.Common Pitfalls:Students sometimes mistakenly change the sign of the x coordinate instead of the y coordinate for reflection in the x axis, which actually describes a reflection in the y axis. Another common mistake is swapping coordinates, which corresponds to reflection in the line y = x. Remember that the x axis affects only the vertical coordinate y when reflecting.
Final Answer:(1, -4)
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