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# C2 Log queston. watch

1. How would you go about solving this?

Can you go through it in simple stages and stating any rules you are using, cheers question is q4 January 2009 edexcel.

Edit: Solved, forgive me I am a fool.
2. Assuming they are the same base you can say (4-x)/x^2 = 5
3. (Original post by Ben121)
Assuming they are the same base you can say (4-x)/x^2 = 5
Is it that easy? :O.
Pity the fool, I just wasted a good half hour trying to figure it out and did not know such a rule existed.
4. ...
5. (Original post by chaosdestro0)
Is it that easy? :O.
Pity the fool, I just wasted a good half hour trying to figure it out and did not know such a rule existed.
Its not really a rule... more just thinking logically... or logarithically.. lol

Aslong as there the same base.. its the same as saying 2*(4-x)/x^2 = 2*5

...and you just divide both sides by 2 to get (4-x)/x^2 = 5.

Same kinda thing
6. (Original post by chaosdestro0)
Is it that easy? :O.
Pity the fool, I just wasted a good half hour trying to figure it out and did not know such a rule existed.
Sure. Just put the base of the log to the power of each side. Eg, if it's log to base e, then just use the exponential function on both sides and this will get rid of both logs.
7. (Original post by beelz)
lol its not really a rule, its just common sense
i wouldn't go as far to say that.
8. Sorry to butt in, but could someone be so kind to talk me through the question please? I missed the lesson on this, so I'm not really sure how to go about it. Much appreciated
9. You should know how to solve (4-x)/x^2 = 5 from core 1. Multiply both sides by x^2 and then you have a quadratic.
10. (Original post by Ben121)
You should know how to solve (4-x)/x^2 = 5 from core 1. Multiply both sides by x^2 and then you have a quadratic.
I know how to solve that , I just fricken hate logs and they need to be nuked from orbit.
I can deal with them, but not apply logic towards as them. It might be due to the fact that we only just rush through them learning rules and not going into hard questions.
11. (Original post by Evanesyne)
Sorry to butt in, but could someone be so kind to talk me through the question please? I missed the lesson on this, so I'm not really sure how to go about it. Much appreciated
Do you know what logarithms are?
12. (Original post by HedonisticMe)
i wouldn't go as far to say that.
why not?
13. (Original post by j.alexanderh)
Do you know what logarithms are?
Kind of.

But oh, I just realised my mistake. I've been trying to solve 4-x/x2 = log5, when it should have been just 5. I got x= 4/5 and -1. Is that right?
14. (Original post by Evanesyne)
Kind of.

But oh, I just realised my mistake. I've been trying to solve 4-x/x2 = log5, when it should have been just 5. I got x= 4/5 and -1. Is that right?
Yep. Are you sure you understand completely now?
15. (Original post by j.alexanderh)
Yep. Are you sure you understand completely now?
Yep. Just about the only topic I understand now
16. (Original post by Evanesyne)
Yep. Just about the only topic I understand now

(it's about maths so it's on topicish)

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