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# OCR C3 Help?! Tweet

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1. OCR C3 Help?!
the graph y=e^x is transformed to y=e^kx

answer is stretch of 1/k in x direction.

But why is it not a stretch of e^k? since e^x multiplied by e^k is e^kx
2. Re: OCR C3 Help?!
(Original post by Super Mario 64)
the graph y=e^x is transformed to y=e^kx

answer is stretch of 1/k in x direction.

But why is it not a stretch of e^k? since e^x multiplied by e^k is e^kx
3. Re: OCR C3 Help?!
(Original post by raheem94)
Can you explain why it is 1/K please ?
4. Re: OCR C3 Help?!
(Original post by Super Mario 64)
the graph y=e^x is transformed to y=e^kx

answer is stretch of 1/k in x direction.

But why is it not a stretch of e^k? since e^x multiplied by e^k is e^kx
Oh I remember coming up with a way to explain transformations I'll simplify it with y = kx as it's the same in principle.

Basically, with a normal y=x graph, y takes on it's "correct" value straight away. With y = 2x, the y value reaches the normal y=x value twice as quickly, meaning the graph is compressed horizontally.

e.g. with y = x, y = 4 when x = 4, but with y = 2x, y reaches 4 when x = 2 instead, which is twice as 'quickly' if you try to consider the x-axis as a sort of timescale.

Equally with y = x + 1, y reaches the value of 4 one "x-unit" early, meaning the graph shifts to the left.

Hopefully that makes sense, it certainly helped me to get my head round it.
5. Re: OCR C3 Help?!
(Original post by kontemptXD)
Can you explain why it is 1/K please ?

So this represents a horizontal stretch of scale factor
6. Re: OCR C3 Help?!
(Original post by Junaid96)
Oh I remember coming up with a way to explain transformations I'll simplify it with y = kx as it's the same in principle.

Basically, with a normal y=x graph, y takes on it's "correct" value straight away. With y = 2x, the y value reaches the normal y=x value twice as quickly, meaning the graph is compressed horizontally.

e.g. with y = x, y = 4 when x = 4, but with y = 2x, y reaches 4 when x = 2 instead, which is twice as 'quickly' if you try to consider the x-axis as a sort of timescale.

Equally with y = x + 1, y reaches the value of 4 one "x-unit" early, meaning the graph shifts to the left.

Hopefully that makes sense, it certainly helped me to get my head round it.
Thanks for the explanation! But wouldn't y=x+1 mean it shifts 1 unit in the positive Y direction?
7. Re: OCR C3 Help?!
(Original post by Super Mario 64)
Thanks for the explanation! But wouldn't y=x+1 mean it shifts 1 unit in the positive Y direction?
Same thing in this case, as f(x+1) = f(x) +1 (for this particular line) If I tok y = (x+1)^2 then it would be a shift 1 to the left, definitely not up.