in `2 log x- log 4= 2` solve for x

All high school algebra is posted here.

Moderator: ChangBroot

Forum rules
To type int use \`int\` and the same way to type sqrt simply type \`sqrt\` or Please view the examples forum.

As you type, live preview is displayed so you know exactly what are you typing.

in `2 log x- log 4= 2` solve for x

Postby Galaxy » Tue 12 April, 2011 18:14

how can I solve for x in in `2 log x- log 4= 2` ?
Posts: 22
Joined: Sat 19 March, 2011 14:54

Re: in `2 log x- log 4= 2` solve for x

Postby barnamah » Tue 12 April, 2011 18:24

to solve for x in `2 log x- log 4= 2` we can simplify it so we can find X.
for the term `2logx` we can wire it as `logx^2` putting it together we have:

Now if we have `logA-logB` we can write it as `log(A/B)` (we have log with the same base 10 here) applying this rule we have:
to solve for x we should know that `logA=B` to find A is `10^B=A` . Remember when log does not have the base such as `log_(5)x=3` means it is based on 5. In our case it is based 10 and we don't write base 10 because everyone knows that.

Applying this rule we can write `10^2=x^2/4` and now we got rid of log, we can solve for x.
Simplify for `10^2=100` we can write `100=x^2/4`
Multiply both side by 4 we have: `4*100=x^2/4*4` the 4 on right cancel out and we got:
`400=x^2`. Now solve for x, we take the square of root of both side:
`sqrt400=sqrt(x^2)` the square root and root cancel out and we have left with x on the right.

so `x=sqrt400=20`
Explore and know. That is asked.
User avatar
Posts: 102
Joined: Mon 14 March, 2011 08:37
Location: Canada

Return to High School Algebra

Who is online

Users browsing this forum: Bing [Bot] and 1 guest