A.) Which relation is NOT a function?
b.)Explain using the definition.
{Hint: A function is a relation that pairs each domain(x) value with EXACTLY ONE range(y) value.}
Relation A: (-5,1),(-4,1),(-3,1),(-1,5), (1,7)
Relation B: (-2,3), (0,1), (1, 2), (2-4), (0,-7)

Relation A is not a function.

Step-by-step explanation:

By definition, a function must have a single unique y-value output for each x value. In Relation A the same y-value 1 appears for 3 different x-values.

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.