Question

State the co-ordinates of the images of the following points under reflection in the $x$-axis:

(i) $(3,-9)$

Answer 1

Given point: $(3,-9)$

Reflection in the $x-\text{axis},M_x(x,y)=(x,-y)$

$\Rightarrow M_x(3,-9)=(3,9)$

$\therefore$ The co-ordinates of the image of the given point under reflection in the $x$-axis are $(3,9)$.