Transformations

Identity · 2007-10-27 22:46:34

Please explain why! Thanks

I think the hardest bit I don't get is how to explain the dilations!

Last edited by Identity (2007-10-27 22:54:59)

mathsyperson · 2007-10-28 10:30:20

You have x².

Firstly, enlarge the graph with scale factor 1/2 with the y axis as the line of enlargement.
(As in, move every point halfway between its current position and the y axis.) This makes it (2x)².

Second, translate the graph with vector (6,0). (Shift it 6 places to the right). This makes your graph (2x-6)².

Now enlarge the graph with scale factor -3 with the x axis as the line of enlargement to get -3(2x-6)².

Finally, translate it with vector (0,4) to get -3(2x-6)²+4.

Identity · 2007-10-28 17:10:57

I thought the x-coordinate should move by a vector (3,0), since we have (2(x-3))² ?

JaneFairfax · 2007-10-28 23:39:12

(3,0) is when translating y = x[sup]2[/sup], (6,0) is when translating y = (2x)[sup]2[/sup].

You could also rewrite equation of the new curve as

and save yourself one transformation in the process. (Namely, you only need three rather than four transformations: apply (3,0) translation, scale vertically by −12, and apply (0,4) translation.)

Identity · 2007-10-29 02:47:41

Okk, thanks Jane and mathsy, transformations is still pretty confusing to me, hope i did well on the test

Identity · 2007-10-29 04:52:36

Ok this was a question on the test:

Find the image of this graph after a dilation of 3 from the x axis, a reflection in the y axis, and finally a translation of 2 units in the positive direction of the y-axis.

I did this:

Let (x,y) map on to (x', y')

Then

So

Is that right?

I have a feeling it is wrong...

Last edited by Identity (2007-10-29 04:54:18)

Math Is Fun Forum

#1 2007-10-27 22:46:34

Transformations

#2 2007-10-28 10:30:20

Re: Transformations

#3 2007-10-28 17:10:57

Re: Transformations

#4 2007-10-28 23:39:12

Re: Transformations

#5 2007-10-29 02:47:41

Re: Transformations

#6 2007-10-29 04:52:36

Re: Transformations

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