Triangle ABC is reflected across the x -axis. If the coordinates of the original shape are A(−4,−1) , B(−5,−2) , and C(−10,−1) , what are the coordinates of A′ , B′ , and C?

When a shape is reflected across the x-axis, the y-coordinates are negated while the x-coordinates remain the same.

The coordinates of the reflected points are:
A' = (-4,1)
B' = (-5,2)
C' = (-10,1)