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# Logs

Maths and statistics discussion, revision, exam and homework help.

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1. Logs
Hi I don't get this question

log2x+log4x=2

:d
2. Re: Logs
(Original post by avtar95)
Hi I don't get this question

log2x+log4x=2

:d
First of all you need to have the same bases, presuming the 2 and 4 are representing base numbers?

Are you familiar with the change of base law?
3. Re: Logs
(Original post by dslc)
First of all you need to have the same bases.

Are you familiar with the change of base law?
could you help
4. Re: Logs
(Original post by avtar95)
could you help
Well is the question log2x+log4x=2?
5. Re: Logs
(Original post by dslc)
Well is the question log2x+log4x=2?
yes
6. Re: Logs
(Original post by avtar95)
yes
Okay so you can use the change of base law which is: logax = logbx/logba

So log4x becomes log2x/log24

Does this help?
7. Re: Logs
(Original post by avtar95)
yes
log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2
8. Re: Logs
(Original post by dongonaeatu)
log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2
yes
9. Re: Logs
(Original post by dongonaeatu)
log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2
would it be 64
10. Re: Logs
(Original post by avtar95)
would it be 64
yes
11. Re: Logs
(Original post by dongonaeatu)
yes

in the answer book it is 2.52
12. Re: Logs
(Original post by avtar95)
in the answer book it is 2.52
oh... sorry im not that good with logs

its definitely log8x though
13. Re: Logs
log2x + log4x = 2

log2x + log2x/log24 = 2

log2x + log2x/2 = 2

2log2x + log2x = 4

3log2x = 4

log2x^3 = 4

x^3 = 16

x = 2.52(3sf)

Ask if you are confused by anything.
14. Re: Logs
(Original post by dongonaeatu)
oh... sorry im not that good with logs

its definitely log8x though
it's on the c2 cd
15. Re: Logs
(Original post by Joshmeid)
log2x + log4x = 2

log2x + log2x/log24 = 2

log2x + log2x/2 = 2

2log2x + log2x = 4

3log2x = 4

log2x^3 = 4

x^3 = 16

x = 2.52(3sf)

Ask if you are confused by anything.
dont understand the second step
16. Re: Logs
(Original post by Joshmeid)
log2x + log4x = 2

log2x + log2x/log24 = 2

log2x + log2x/2 = 2

2log2x + log2x = 4

3log2x = 4

log2x^3 = 4

x^3 = 16

x = 2.52(3sf)

Ask if you are confused by anything.
y did u do log2x / log24
17. Re: Logs
(Original post by dongonaeatu)
log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2
No, you are making mistake again.

18. Re: Logs
(Original post by avtar95)
y did u do log2x / log24
The change of base rule.

19. Re: Logs
(Original post by raheem94)
No, you are making mistake again.

is that rule just for log2x and log4x i've never been taught that
20. Re: Logs
(Original post by raheem94)
The change of base rule.

could u put that in letters

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