log.abit confused?
Posted by admin
4dimensions? asked:
3log(b2)x=log(b2)8
can i just move the left side to the right like this:
3=[log(b2)8]/[log(b2)x]
so
3=log(b2)[8-x]
then:
2^3=8-x…….but if this way is right then x would be undefined, so i though of another way to do it:
log(b2)(x^3) = log(b2)8
cancle the logs:
x^3=8
x=2
how come this way works? couls some one explain this to me, thanks
oooo i got it so the first part i can use negative?(subtraction?
Roger
3log(b2)x=log(b2)8
can i just move the left side to the right like this:
3=[log(b2)8]/[log(b2)x]
so
3=log(b2)[8-x]
then:
2^3=8-x…….but if this way is right then x would be undefined, so i though of another way to do it:
log(b2)(x^3) = log(b2)8
cancle the logs:
x^3=8
x=2
how come this way works? couls some one explain this to me, thanks
oooo i got it so the first part i can use negative?(subtraction?
Roger
December 24th, 2007 at 5:01 pm
Hi,
3log(b2)x=log(b2)8
log(b2)x³=log(b2)8
x³ = 8
x = 2
December 26th, 2007 at 9:00 am
I’ll use lg to mean log in base 2.
3lg(x) = lg(8)
lg(x^3) = lg(8)
x^3 = 8
x = 2
What you did with converting a quotient of logs into the log of the difference doesn’t work. It’s the other way around: The log of a quotient is the difference of the logs.
Also, if 2^3 = 8-x then x is 0, not undefined.