# Thread: Solve equation for X: 125^(3x) = 1/5^(18) (so far, I have (125)^{3x} * 5^{18} = 1)

1. ## Solve equation for X: 125^(3x) = 1/5^(18) (so far, I have (125)^{3x} * 5^{18} = 1)

Solve this equation for X

1253x =1/518

So far I have , (125)3x * 518 = 1

What kind of steps are required here?

Or I was thinking perhaps writing the expression as such

1253x = 5-18

2. Originally Posted by richiesmasher
1253x = 5-18
Looks good. How do we get a simple equation from this?

3. Originally Posted by richiesmasher
1253x = 5-18
Hint: when you are solving exponential equations, it's a good idea to be familiar with powers of 2, 3, 4, 5 so you can recognize them when you see them. In particular, since one base is 5, it would be very nice if 125 was a power of 5, wouldn't it?

4. Originally Posted by lev888
Looks good. How do we get a simple equation from this?
Got it:
1253x =5-18

= (53)3x= 5-18

59x=5-18

(because both bases are the same)

9x=-18
x= -2

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•