Question

Difficulty: MediumTransformations in the Coordinate Plane

A geometric shape on a coordinate grid has a vertex at T(2,−5)T(2, -5). The shape is translated 33 units to the left and 44 units up, and then the resulting image is reflected across the yy-axis. What are the coordinates of the final image of vertex TT?

  1. A
    (−5,−1)(-5, -1)
  2. B
    (−6,−8)(-6, -8)
  3. (1,−1)(1, -1)Answer
  4. D
    (1,−9)(1, -9)
  5. E
    (−5,−9)(-5, -9)

Answer

The correct coordinates of the final image of vertex TT are (1,−1)(1, -1).
To find the coordinates of the final image, we apply the transformations in the specified order. First, translating the point (2,−5)(2, -5) by 33 units to the left subtracts 33 from the xx-coordinate, and translating it 44 units up adds 44 to the yy-coordinate: (2−3,−5+4)=(−1,−1)(2 - 3, -5 + 4) = (-1, -1). Second, reflecting the point (−1,−1)(-1, -1) across the yy-axis negates the xx-coordinate while keeping the yy-coordinate the same: (−(−1),−1)=(1,−1)(-(-1), -1) = (1, -1).

Step-by-Step Solution

1
Apply the horizontal and vertical translations to the pre-image point T(2,−5)T(2, -5).
Translating 33 units left subtracts 33 from the xx-coordinate (2−3=−12 - 3 = -1). Translating 44 units up adds 44 to the yy-coordinate (−5+4=−1-5 + 4 = -1). The intermediate point is (−1,−1)(-1, -1).
A translation of hh units horizontally and kk units vertically maps (x,y)(x, y) to (x+h,y+k)(x + h, y + k).
2
Reflect the intermediate point (−1,−1)(-1, -1) across the yy-axis.
Reflecting across the yy-axis negates the xx-coordinate while keeping the yy-coordinate the same: (−(−1),−1)=(1,−1)(-(-1), -1) = (1, -1).
A reflection across the yy-axis maps any point (x,y)(x, y) to (−x,y)(-x, y).

Key Concept

Transformations in the Coordinate Plane
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