Answer:
no
Explanation:
You want to know if point (1, 9) becomes point (1, -9) after reflection across the y-axis.
Reflection
The line of reflection is the perpendicular bisector of the segment joining a point with its reflected image.
The attachment shows the two point A(1, 9) and A'(1, -9). The perpendicular bisector of the segment between them is the x-axis.
(1, -9) is NOT the reflection of (1, 9) across the y-axis.
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Additional comment
The point marked B is the reflection of A across the y-axis. Its coordinates are (-1, 9).
Reflection across the y-axis changes the sign of the x-coordinate.
Reflection across the x-axis changes the sign of the y-coordinate.
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