Respuesta :
Answer
Coordinates of point B':
B' = (-1, -4)
Explanation
To reflect a point or a figure across the x-axis we use the rule:
[tex](x,y)[/tex]→[tex](x,-y)[/tex]
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)

Answer:
B'( -1 , -4).
Step-by-step explanation:
Given : Triangle ABC is shown. A is at 2, 1. B is at negative 1, 4. C is at 3, 7. If triangle ABC is reflected over the x-axis,
To find : which of the following shows the coordinates for point B'.
Solution : We have given A (2,1 )
B ( -1,4)
C(3,7)
If it is reflected over x axis then,
By the reflection over x axis rule (x , y) →→→→( x , -y).
Then , B(-1 , 4) →→→→ B'( -1 , -4).
Therefore, B'( -1 , -4).