# Logarithms

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#1
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
0
6 years ago
#2
(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
You've posted in the wrong section. Need to post it in the Maths forum.

Make use of:

log(10)x = y

=> x = 10^y.
0
6 years ago
#3
(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?

Use the the rules

and

and that

means that
0
6 years ago
#4
You've posted in the wrong section. Need to post it in the Maths forum.

Make use of:

log(10)x = y

=> x = 10^y.
Everything's to base 2 in this question, so using base 10 logs is just going to confuse things!
0
6 years ago
#5
(Original post by davros)
Everything's to base 2 in this question, so using base 10 logs is just going to confuse things!
That was just an example of the general rule.
0
6 years ago
#6
(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
Collect the logs on one side of the equation, combine them and then convert to index form.
0
6 years ago
#7
That was just an example of the general rule.
But you didn't quote the general rule (see TenOfThem's post)

(I see what you were trying to do, but the '10' in your post was completely arbitrary)
0
6 years ago
#8
(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?

that is

and finish with that

as the function of f=log x is bijection

from the

follows that

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