# log equation

• February 3rd 2009, 02:05 PM
jimstewart_NC
log equation
Hi,

I need a bit of help to solve a log equation. Any help is so much appreciated!

I need to solve this logarithm for x:

log3x81 = 2

(where 3x is the base of the log)

I was thinking of booting the log to get:

81 = 3x^2

but then what? or am I on the wrong track to solving.

Thanks,

Jim.
• February 3rd 2009, 02:14 PM
topher0805
Quote:

Originally Posted by jimstewart_NC
Hi,

I need a bit of help to solve a log equation. Any help is so much appreciated!

I need to solve this logarithm for x:

log3x81 = 2

(where 3x is the base of the log)

I was thinking of booting the log to get:

81 = 3x^2

but then what? or am I on the wrong track to solving.

Thanks,

Jim.

You are correct that:

$(3x)^2 = 81$

Now take the square root of both sides:

$3x = 9$

Divide both sides by 3:

$x = 3$