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# c3 functions watch

1. I was doing q6c on this paper and ran into a misunderstanding

QP: https://07a69ccf283966549a9350d1a669...%20Edexcel.pdf

surely we square and cube everything inside the bracket of the g(x) function? (as shown in the image i uploaded)

can someone explain why this is wrong, the x value in the g(x) function is 2x so surely we square and cube that?

Zacken
Attached Images

2. (Original post by Katiee224)
Zacken
No, the x value is x. That's all you're changing.

If it helps, you could write it as g(x) = ln 2 + ln x.

So g(x^2) = ln 2 + ln x^2 = ln (2x^2).
3. (Original post by Zacken)
No, the x value is x. That's all you're changing.

If it helps, you could write it as g(x) = ln 2 + ln x.

So g(x^2) = ln 2 + ln x^2 = ln (2x^2).
2 minute wait for a reply zacken, you're slacking

ah ok I see now, what if we had '2y' in the bracket, so

g(x) = ln(2y)

and wanted to work out g(x^2)?

or is that not possible as it has to be a function of x?
4. (Original post by Katiee224)
2 minute wait for a reply zacken, you're slacking

ah ok I see now, what if we had '2y' in the bracket, so

g(x) = ln(2y)

and wanted to work out g(x^2)?

or is that not possible as it has to be a function of x?
Well, yeah. Then y is basically just a constant instead of a variable, so g(x) = g(x^2) = g(x^elephant) = ln(2y).

(basically what you said about it having to be a function of x)
5. (Original post by Zacken)
Well, yeah. Then y is basically just a constant instead of a variable, so g(x) = g(x^2) = g(x^elephant) = ln(2y).

(basically what you said about it having to be a function of x)

hahaha okay thanks for the help, btw do you recommend doing TeeEm's papers for c3/c4 revision or get the edexcel past papers done first?

how have you been revising for these subjects?
6. (Original post by Katiee224)
hahaha okay thanks for the help, btw do you recommend doing TeeEm's papers for c3/c4 revision or get the edexcel past papers done first?

how have you been revising for these subjects?
Get the Edexcel papers done first.

I did them in Jan.
7. (Original post by Zacken)
Get the Edexcel papers done first.

I did them in Jan.
haha you cocky lil

did you get 100 UMS in all of them I'm guessing?
8. (Original post by Katiee224)
haha you cocky lil

did you get 100 UMS in all of them I'm guessing?
Something like that.

I'm sure you'll do fine!
9. (Original post by Zacken)
Something like that.

I'm sure you'll do fine!
Gotta let me know your maths results when you get them, so I can stare at your UMS in envy
10. (Original post by Katiee224)
Gotta let me know your maths results when you get them, so I can stare at your UMS in envy
It's nothing special. UMS sucks anyway.

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