I really get confused about the negative and positive signs.

Question

So, lets say i would want to reflect (9,-5) over the x-axis, right after that i don't know to change the sign on 9 or to change 5 to a positive. Also, the reflection over the y-axis. There is also problems that have dilation. For example,(-12,-8)--> dilation with K= 1/4 --> (  ,  ). 

Answer 1

 

When reflecting a point across the x-axis, you simply change the sign of the y-coordinate.

To reflect (9, 5) across the x-axis,

 

     (9, -5)   ---- reflection across x-axis ----> (9, 5)

 

When reflecting a point across the y-axis, you simply change the sign of the x-coordinate.
To reflect (9, 5) across the y-axis,

 

     (9, -5)    ---- reflection across y-axis ----> (-9, -5)

 

To dilate a point, you simply multiply both the x and y coordinate by the scale factor.

 

     (-12, -8)  --- dilation with K = 1/4 ------> (-3, -2)

 

      NOTE:  1/4 of -12 = -3 .... 1/4 of -8 = -2