jaco291096
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how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
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dan94adibi
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(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.
Show some working out and I will help you.

Make use of:

log(10)x = y

=> x = 10^y.
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TenOfThem
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(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
3 + 2\log _2x = \log _2y

Use the the rules

a\log b = \log b^a

and

\log p - \log q = \log \frac{p}q}

and that

\log _a b = c means that b = a^c
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davros
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(Original post by dan94adibi)
You've posted in the wrong section. Need to post it in the Maths forum.
Show some working out and I will help you.

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!
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dan94adibi
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(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.
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brianeverit
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(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.
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davros
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(Original post by dan94adibi)
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)
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ztibor
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(Original post by jaco291096)
how do you work out 3+2logbase2of x=logbase2 of y, show that y=8x^2 ?
Start with

\displaystyle c=\log_a a^c

that is \displaystyle 3=\log_2 2^3=\log_2 8

and finish with that

as the function of f=log x is bijection

from the \displaystyle \log p=\log q

follows that

\dosplaystyle p=q
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