What does the state me f(3)=18 mean

Hey there! I'm happy to help!

The normal function notation is f(x)=something. If you switch the x, the x is the function switches. If your function was f(x)=2x+1 and you wanted to plug in an x value of 2, you would write f(2)=2(2)+1 which is also f(2)=5.

So, in your case, this means that if you input 3 into the function, your result will be 18.

Have a wonderful day! :D

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'.

your answer is the frist one

hop i