# Thread: Exponential Question again...

1. ## Exponential Question again...

HI! im stuck with another exponential question!!

Solve the following equation:

$\dpi{150} 64^x-8^{x+1}+16=0$

Answer is $\dpi{150} x=\frac{2}{3}$

I keep getting the wrong answer. Can somebody tell me what is wrong with my working?
Thanks! I would appreciate it a lot!

My working:

$\dpi{150} 64^x-8^{x+1}+16=0$

$\dpi{150} 2^{6x}-2^{3x+3}+2^4=0$

$\dpi{150} 6x-3x-3+4=0$

$\dpi{150} 3x+1=0$

$\dpi{150} x=-\frac{1}{3}$

3. ## Re: Exponential Question again...

Thank you ibdutt! You've been a great help to me and my homework haha
But mind me asking. Can you help me see what is wrong with my working? thank you very very much!

4. ## Re: Exponential Question again...

Originally Posted by pumbaa213
Thank you ibdutt! You've been a great help to me and my homework haha
But mind me asking. Can you help me see what is wrong with my working? thank you very very much!
What's wrong with your working is that when you have a sum of exponential terms, you can't just "get rid of" the bases like you did.

5. ## Re: Exponential Question again...

How did you get 6x-3x-3+4= 0. There is no way that you can get that. OK