Answer:
a) In a coordinate plane, the horizontal axis is the x-axis, and the vertical axis is the y-axis.
So, a point (x, y) is at:
A horizontal distance of x units from the origin.
A vertical distance of y units from the origin.
So the point (3, -7) is at:
3 units at the right from the origin
7 units downwards (because is a -7) from the origin.
The graph of the point can be seen below:
Now we want to find a reflection across the x-axis.
b) For a general point (x, y), a reflection across the x-axis gives:
(x, -y)
So, if our point P is:
P (5, 1)
The reflection across the x-axis just changes the sign of the y-value, which gives:
(5, -1)
Then the correct option is point C:
(5, -1)