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Hi I don't get this question


Solve, giving your answer to 3 significant figures:


log2x+log4x=2

:d

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Reply 1
Avatar for dslc
dslc
Original post by avtar95
Hi I don't get this question


Solve, giving your answer to 3 significant figures:


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?
Reply 2
Avatar for avtar95
avtar95
OP
6
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
Reply 3
Avatar for dslc
dslc
Original post by avtar95
could you help


Well is the question log2x+log4x=2?
Reply 4
Avatar for avtar95
avtar95
OP
6
Original post by dslc
Well is the question log2x+log4x=2?


yes
Reply 5
Avatar for dslc
dslc
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?
Reply 6
Avatar for dongonaeatu
dongonaeatu
Original post by avtar95
yes


log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2
Reply 7
Avatar for avtar95
avtar95
OP
6
Original post by dongonaeatu
log2x+log4x=2

so log2x+log4x

is the same as log2x times log4x

so its log8x=2


yes
Reply 8
Avatar for avtar95
avtar95
OP
6
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
Reply 9
Avatar for dongonaeatu
dongonaeatu
Original post by avtar95
would it be 64


yes
Reply 10
Avatar for avtar95
avtar95
OP
6
Original post by dongonaeatu
yes



:confused: in the answer book it is 2.52
Original post by avtar95
:confused: in the answer book it is 2.52


oh... sorry im not that good with logs

its definitely log8x though
Reply 12
Avatar for Joshmeid
Joshmeid
5
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.
Reply 13
Avatar for avtar95
avtar95
OP
6
Original post by dongonaeatu
oh... sorry im not that good with logs

its definitely log8x though


it's on the c2 cd
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
Reply 15
Avatar for avtar95
avtar95
OP
6
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
Reply 16
Avatar for raheem94
raheem94
13
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.

log2x+log4x≠log2x×log4x log_2x+log_4x \not= log_2x \times log_4x
Reply 17
Avatar for raheem94
raheem94
13
Original post by avtar95
y did u do log2x / log24


The change of base rule.

log4x=log2xlog24 \displaystyle log_4x = \frac{log_2x}{log_24}
Original post by raheem94
No, you are making mistake again.

log2x+log4x≠log2x×log4x log_2x+log_4x \not= log_2x \times log_4x


is that rule just for log2x and log4x i've never been taught that
Reply 19
Avatar for avtar95
avtar95
OP
6
Original post by raheem94
The change of base rule.

log4x=log2xlog24 \displaystyle log_4x = \frac{log_2x}{log_24}


could u put that in letters

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