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# C3 Graph Transformations watch

1. Describe a sequence of two geometrical transformations that maps the graph of y=f(x) onto the graph of y=f(2x+2).

The answer is a stretch of scale factor 1/2 in the x direction followed by a translation one unit to the left. I get this because it's like you go f(x) -> f(2x) -> f2(x+1) so f(2x+2).

My answer was wrong because I put them the other way round. I thought that I could say a translation one unit to the left giving f(x+1) followed by a stretch sf 1/2 in x direction giving f2(x+1) and therefore the answer.

Am I right in saying that such a combination actually gives you f(2x+1)? Because the stretch means replacing x with 2x rather than multiplying the whole thing by 2? I hope that made sense to somebody lol
2. The 2 only affects the x, not the 1.
3. (Original post by hannah412)
The 2 only affects the x, not the 1.
Cool I thought that might be it. Thanks
4. i would say translate 2 left then squash 1/2 horizontally ?

5. (Original post by the bear)
i would say translate 2 left then squash 1/2 horizontally ?

Yeah that works too! My confusion was with thinking the stretch affected more than just the x.
6. (Original post by the bear)
i would say translate 2 left then squash 1/2 horizontally ?

I tend to aswell. Means you don't have the stretch to worry about.
7. Never say "squash". Mark schemes are clear that it must be "stretch".
8. it can be written correctly 2 different ways, but only one way is sensible (the other is for maths perverts)
9. Page 10 of ocr.org.uk/Images/60809-examiners-reports-january.pdf says candidates must say "one-way stretch", not "squash" or "squeeze".
10. (Original post by TeeEm)
it can be written correctly 2 different ways, but only one way is sensible (the other is for maths perverts)
Is it true to say that you can look at what's happening in the brackets first and mention the translation before the stretch and then you look outside the brackets and do the stretch before the translation.

e.g. x^2 to 2(3x-6)^2 -4 would be
translation in x by 6
stretch in x sf 1/3
stretch in y sf 2
translate in y by -4
11. yes I think so.

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