Question

Find x if :log(b8)+log(bx^2) =log(bx)

Answer 1

Use those logarithm rules, silly.

Go and rewrite the left side as \[log_{b}(something)\]

It'll be quite easy after that.

Answer 2

8x^2=x

Answer 3

Note: x cannot be zero, because log(0) doesn't exist for any base

Answer 4

x(8x-1) =0

x=(1/8)

Answer 5

confused

Answer 6

remember the logarithm rules? specifically this one:
\[log_{b}x+log_{b}y=log_{b}xy\]
Use that to change the left side. Do that first, then the next step.

Answer 7

how do you go from 8x2=x to x=1/8???

Answer 8

Chrissy, do what I said, you'll see. You are also reading elec's post wrongly.

Answer 9

Are my posts all on one line?

I think there is something wrong with this site.

I usually space things ot but obviously you can't see the spaces I put in.

Answer 10

I understand that logb8+logbx^2= log8x^2, what is the next step Ian??

Answer 11

Oh, okay.

\[log_{b}8+log_{b}x^{2}=log_{b}x\]
\[log_{b}8x^{2}=log_{b}x\]
\[8x^{2}=x\]

Answer 12

right

Answer 13

Oh, do you want after all of that?

\[8x^{2}-x=0\]
This is sort of like a quadratic equation, if you think about it.

Answer 14

I have not started quadratic equations yet

Answer 15

Really? logarithms are usually after those.

Factorize the left hand side.

Answer 16

I can only prime factorize

Answer 17

You cannot factorize algebraic expressions? For example:
ab+ac factorized is a(b+c)
The factors are a and (b+c)

Answer 18

I can only prime factorize

Answer 19

not yet no. in class, we have started linear equations, and what I would call simple logarithms. If I had known that I needed to know more stuff before starting these logarithms I would I waited.

Answer 20

ohhh.

Well, to explain it:

\[8x^{2}-x=0\]
you factorize it. Do you know the distributive property? You can use hat to see this step.
\[x(8x-1)=0\]
so something multiplied by something is 0. In order for that to be true, one of the somethings must be zero, or both of them are zero. so...

x=0 or 8x-1=0
x cannot be 0 because the log of 0 is undefined. So it must be 8x-1=0
8x=1
x=1/8

Answer 21

I can only prime factorize

Answer 22

I dont get it, but Thanks for your help