Answer:
Coordinates of point B':
B' = (-1, -4)
Explanation
To reflect a point or a figure across the x-axis we use the rule:
→
In other words, we multiply the y-coordinate of our points by -1, while leaving the original x-coordinate as it is.
Let's apply the rule to every point of our triangle :
A = (2, 1)
A' = (2, 1*-1) = (2, -1)
B = (-1, 4)
B' = (-1, 4*-1) = (-1, -4)
C = (3, 7)
C' = (3, 7*-1) = (3, -7)
All the credit goes to cerverusdante
