Answer:
0
Step-by-step explanation:|-2 - (-1)| =
|-2 + 1| =
| -1 | =
1.
So, we're one unit away from y = -1. If we're one unit ABOVE y=-1, we need to move the point to be one unit BELOW it instead. And if we're one unit BELOW y = -1, we need to move the point to be one unit ABOVE it.
Since the point has a y-coordinate of -2, its BELOW the line y = -1, by 1 unit. Now we change the y-coordinate so its instead ABOVE y = -1, by 1 unit:
(y-coordinate of reflection line) + (number of units above that line) =
-1 + 1 =
0.
Our new y-coordinate is 0, so the point is now at
(7, 0).
A more mechanical, but less intuitive approach is as follows:
Let L = the y-coordinate of the line, and
P = the y-coordinate of the point.
The new y-coordinate is 2L - P.
In this case, L = -1, and P = -2. So we have
2L - P =
2(-1) - (-2) =
-2 -(-2) =
0.
