Question

Which type of transformation is described by (x,y) → (-x, y)?

a reflection across the y-axis

a rotation of 90° about the origin

a dilation of scale factor - 1

a rotation of 180° about the origin

Answer 1

Reflection across the x-axis.

Explanation:

Use squared paper and plot some coordinate points.

For example: (2,3) and (−3,−2) and reflect them in the x-axis. You should obtain the following results.

(2,−3) and (−3,2) respectively.

(Note that the x-coordinate remains unchanged, while the y-coordinate is the negative of the original point.In general this can be expressed as: Under reflection in the x-axis (x,y)→(x,−y))