# Transformations

• Jun 2nd 2010, 12:00 AM
bogan
Transformations
I need some help with these questions. It's asking me to find the image of the line with the equations y=2x-3 under each of these instances:

a) a rotation of 90 degrees about the origin.
b) a reflection in the y-axis
c) a translation of 2 units parallel to the x-axis in positive direction.

a) is x=2y-3? I basically guessed this answer, but i'm not sure WHY it is this answer lol.
b) y=-2x+3?
c) i know that the line crosses through point (3/2,-3) does this mean i move this point by 2 x units and substitute this into y=mx+c equation?

Cheers
• Jun 2nd 2010, 04:27 PM
TKHunny
#1) You must think about what you are doing. There never has been, and never will be, a "lol" theorem. (Shake)

You have y = 2x-3

a) 90º rotation about the origin. Think on its properties.

Is there a point that will be on both lines?
Is there a predictable point? How about (0,-3). Where will that go?
Is it acceptable to leave it solved for x, rather than for y?

b) Reflection on y-axis. This is the easiest, I think. Simply substitute -x for x. Done.

c) 2 to the right. This one is almost as easy as b).

The slope will not change.
Where will (0,-3) go? (2,-3)? You're almost done.