00:01
Alright, we're going to be tracking a point through some transformations to get a handle on transformations.
00:08
So suppose that 2 comma 5 is a point on the graph of an arbitrary function, call it f of x.
00:23
What does that mean? that means that 2 .5 has the form x comma f of x.
00:28
Or in other words, f of 2 is equal to 5.
00:36
So, if 2, 5 is on the graph of f of x, then what point can we say, for sure, is on the graph of f of x minus 4? supposing we knew nothing else about f of x.
00:50
We just know 2 .5 something, right? so 2 .5 is up here.
00:57
And we're going to draw the graph, what we know about the graph of f of x minus 4, so we're going to put an empty hole right here because we know that 2 .5 is from here, it must have ended up somewhere else.
01:10
Well, whenever you subtract 4, what you do is you are moving down vertically, right? you're moving down four units.
01:23
So the point that is on the graph of f of x minus 4 is actually 2 .1.
01:28
2 .5 became 2 .1.
01:35
And you'll notice that since the sort of subtraction was on the outside of the f of x, we ended up subtracting it from the output, right? so thinking about it geometrically is one way, but later on, we're going to run into more difficult situations where you probably want to think about it more symbolically.
01:56
So you should get a handle on both points of view.
02:00
So that was that.
02:02
What about a horizontal transformation, like f of x minus.
02:05
4 on the inside.
02:09
So don't forget, whatever you're dealing with vertical transformations, it works the way you would expect.
02:17
Minus means you move in the negative direction, positive means moves and move in the positive direction.
02:24
For horizontal transformations, whenever you are messing with x itself on the inside, it works the opposite.
02:32
So x minus 4 moves the 2 .5 point to the right in the positive direction to 6 .5, right? so 2 .5 becomes 6 .5.
02:51
We can say that 6 .5 is on the graph of f of x minus 4 quantity.
03:02
Right? so what about the transformation negative 7 f of x.
03:11
So we know geometrically that since we're taking the negative, it's going to reflect it around the x -axis, right? and then span it by 7.
03:23
But you might think about this more symbolically.
03:27
You could say that what this does is negative...
03:32
Since negative 7f of 2 is equal to negative 7 times 5, right? because that's what f of 2 is, that you get negative 35.
03:51
Right? so on the graph of this function, negative 7f, you know that you get like one little point right here, 2 .5.
04:03
That is not on the graph.
04:04
It has been moved, it has been reflected, and multiplied to become 2 comma negative 35...