Coordinate Rule: Reflection Across the y-axis
Grade 7 students in Big Ideas Math Advanced 2 (Chapter 2: Transformations) learn the coordinate rule for reflecting a point across the y-axis: (x, y) becomes (-x, y). The x-coordinate changes sign while the y-coordinate remains unchanged, because the y-axis is the line of reflection.
Key Concepts
When reflecting a point across the y axis, the transformation rule is $(x, y) \rightarrow ( x, y)$. The x coordinate changes sign while the y coordinate remains unchanged.
Common Questions
What is the rule for reflection across the y-axis in 7th grade?
The rule is (x, y) to (-x, y). The x-coordinate changes sign, the y-coordinate stays the same. Example: (3, 2) reflects to (-3, 2).
How do you reflect a point across the y-axis?
Change the sign of the x-coordinate while keeping the y-coordinate the same. For (-4, -1), the reflection across the y-axis is (4, -1).
What happens to a point on the y-axis when reflected across it?
A point on the y-axis (x = 0) stays in the same position, because -0 = 0.
What chapter in Big Ideas Math Advanced 2 covers reflection across the y-axis?
Chapter 2: Transformations in Big Ideas Math Advanced 2 (Grade 7) covers coordinate rule for reflection across the y-axis.
How is reflecting across the y-axis different from reflecting across the x-axis?
Across the y-axis, the x-coordinate changes sign: (x, y) to (-x, y). Across the x-axis, the y-coordinate changes sign: (x, y) to (x, -y).