Math Is Fun Forum

saudi_boy

Member

Registered: 2006-11-01

Posts: 41

help me please

dear ALL

could you please show the steps of solution?

thank U.:D:D

pi man

Member

Registered: 2006-07-06

Posts: 251

Re: help me please

First, remember that:

     edited typo mistake...   Thanks Ricky

We need to figure out what to multiply both sides of your first equation.   We want to get the exponents equal:

So multiply both sides of the first equation by 2 raised to the 2x - 1 power:

Last edited by pi man (2006-11-02 09:02:40)

polylog

Member

Registered: 2006-09-28

Posts: 162

Re: help me please

You could also do this:

Now substitute this into the second part:

This has the advantage of only depending on y.

saudi_boy

Member

Registered: 2006-11-01

Posts: 41

Re: help me please

pi man

thank U very much,,,

polylog

yessssss,,

that's good work.

thank you veeeery much..

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: help me please

First, remember that:

This is incorrect.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: help me please

i know that people have already gave solution, but theres my workings out of it

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The Beginning Of All Things To End.
The End Of All Things To Come.

saudi_boy

Member

Registered: 2006-11-01

Posts: 41

Re: help me please

hmmmmmmmmmm,,

What multipied by 2^x-1 equals 2^3x-2 ?.

(2^x-1)(2^2x-1)=2^3x-2

2(2^x-1)^3=2^3x-2

= 2y^3

Is that a correct answer ?

luca-deltodesco

Member

Registered: 2006-05-05

Posts: 1,470

Re: help me please

that is a correct answer, theres nothing wrong in the working out. I just assumed you were meant to use logarithms for this, which really if you know how they work, is a simpler method than yours, since using logarithms requires no real thinking at all. wheras yours requires you to think of something that multiply the first statement to give the second, and then thinking of how to rearrange it to keep it the same, but continaing the original statement in a form you can reduce into an equation containing y, if you know what i mean.

---

The Beginning Of All Things To End.
The End Of All Things To Come.

saudi_boy

Member

Registered: 2006-11-01

Posts: 41

Re: help me please

thank you ALL
:D:cool::cool: