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# Logarithms!!! watch

1. WHY ARE LOGARITHMS SO HARDDDDD.

I've been practising for 12 hours and I still can't grasp it, especially when they ask for damn quadratic logs.

I've been CRYING OVER THIS QUESTION!!!!

Prove that if a^x = b^y = (ab)^xy, then x + y = 1

I'M GOING INSANE X_X

C2 exam... I'll see you in a retake.
2. (Original post by Lord Frieza)
WHY ARE LOGARITHMS SO HARDDDDD.

I've been practising for 12 hours and I still can't grasp it, especially when they ask for damn quadratic logs.

I've been CRYING OVER THIS QUESTION!!!!

Prove that if a^x = b^y = (ab)^xy, then x + y = 1

I'M GOING INSANE X_X

C2 exam... I'll see you in a retake.
Are you sure that the question has two = signs
3. (Original post by Lord Frieza)
WHY ARE LOGARITHMS SO HARDDDDD.

I've been practising for 12 hours and I still can't grasp it, especially when they ask for damn quadratic logs.

I've been CRYING OVER THIS QUESTION!!!!

Prove that if a^x = b^y = (ab)^xy, then x + y = 1

I'M GOING INSANE X_X

C2 exam... I'll see you in a retake.
There's a mistake in this question. x=y=0 is a counterexample.
4. (Original post by notnek)
There's a mistake in this question. x=y=0 is a counterexample.
+1.
5. I think it works if you assume that none of these hold:

x=y=0
a=b=1
a=b=0
6. If you REALLY want to use logs... (as opposed to just exponents)

Then you would log_ab everything. This would give you a new equation.

Split the equation of three into two equation of twos, do some VERY simple algebra to each, and everything you want will come easily.
7. There's no mistake in the question, it's a standard exam style question written exactly like that, can anyone write down a worked solution??!?!?!
8. Please follow the hint I gave and show your working so we can nudge you should you get stuck.

Full solutions are boring.
9. (Original post by notnek)
The question does have mistakes and is definitely not a C2 exam question.

Where did you get the question from? My advice: if the question is making you go insane, give up. Focus on real C2 exam questions.
It's from the edexcel textbook I saw it the other day
10. a^x = b^y = (ab)^xy, then x + y = 1

a^x - b^y = (ab)^xy, then x + y = 1

= (Loga + Logb)^xy = Xloga - ylogb

I am so confused..
11. (Original post by notnek)
The question does have mistakes and is definitely not a C2 exam question.

Where did you get the question from? My advice: if the question is making you go insane, give up. Focus on real C2 exam questions.
It's in the official edexcel C2 book. Mixed exercise 3G Q10. There's no mistake.
12. (Original post by SheldonWannabe)
It's in the official edexcel C2 book. Mixed exercise 3G Q10. There's no mistake.
Yeaah that's the one!

Edit: There's a big fat 'E' next to it.. as in EXAM QUESTION.
13. (Original post by Lord Frieza)
Yeaah that's the one!
I know it off by heart because that's the one logs questions I can't do either.
14. (Original post by SheldonWannabe)
It's in the official edexcel C2 book. Mixed exercise 3G Q10. There's no mistake.
As I showed in my first post, if it's written as the OP posted it, it's wrong.
15. (Original post by SheldonWannabe)
I know it off by heart because that's the one logs questions I can't do either.
You can do the other 11 questions..?\

They are so hard for me
16. (Original post by notnek)
As I showed in my first post, if it's written as the OP posted it, it's wrong.

Dude. -.-
17. (Original post by Lord Frieza)
Yeaah that's the one!

Edit: There's a big fat 'E' next to it.. as in EXAM QUESTION.
Most likely it has been copied from an exam incorrectly.

Can you explain why you negged me? Try inputting x=y=0 and a=b=1.
18. (Original post by Lord Frieza)
Yeaah that's the one!
if then take logs from both sides and form in terms of y and x an expression for a log, base a and b then get another expression in terms of x and y =x and then find an expression for log_a using where you need to remember that
If your stuck here's a bit of guidance for forming your first equation
Spoiler:
Show
(use the power rule)
19. Yeah I remember this question in my Edexcel C2 book, it got me as well.
20. (Original post by notnek)
Most likely it has been copied from an exam incorrectly.

Can you explain why you negged me? Try inputting x=y=0 and a=b=1.
I didn't neg you, but even on the cd it's the same question. There's no mistake whatsoever!

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