Agraphing calculator displays 1.89 x 10^12 as 1.89e12. how do you think it would display 1.89 x 10^-12? what does the e stand for?

What you need to know for this case is that the calculator is using the scientific notation in two different ways:

Way 1:

Way 2:

Where, in both cases:

a, b: they are real numbers.

Therefore, for the following number:

We have an equivalent way is:

The e refers to the exponent to which the base 10 is elevated.

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'.