
We need to solve for x, we need to get x alone

Lets start by removing -5
Add 5 on both sides


Now to isolate x , we need to remove the square from x
To remove square , take square root on both sides

square and square root will get cancelled

So
and 
You have to dive the x and the Y so R=7
Given that triangle <span>STU
is reflected once to map onto
triangle S'T'U'.
Given that triangle STU has
vertices S(8, 6), T(2, 2), U(5, 1).
If vertex T' is at
(2, −2), this means that triangle STU is refrected across the x-axis.
A refrection across the x-axis results in an image that has the same x-value as the pre-image but a y-value that has the opposite sign of the y-value of the pre image.
Thus, a point, say (x, y), refrected over the x-axis will result in an image with coordinate (x, -y)
Therefore, given that the coordinate of S is (8, 6), then the coordinates of vertex S'</span> is (8, -6).