Solve for x

• Sep 25th 2009, 07:26 AM
wannous
Solve for x
• Sep 25th 2009, 07:29 AM
songoku
Hi wannous

I also got x = √50 for the first question :)
• Sep 25th 2009, 07:42 AM
wannous
can u help me with number 2 im not getting the right answer
• Sep 25th 2009, 07:45 AM
Defunkt
$ln(x-7) + ln (x+7) = 0 \Leftrightarrow ln((x-7)(x+7)) = 0$

$\Leftrightarrow e^{ln((x+7)(x-7))} = e^0 \Leftrightarrow (x+7)(x-7) = 1$

$\Leftrightarrow x^2 = 50 \Leftrightarrow x = \sqrt{50}$

Other one:

$ln(x-4) - ln (2x-9) = 0 \Leftrightarrow ln( \frac{x-4}{2x-9}) = 0$

$\Leftrightarrow e^{ln(\frac{x-4}{2x-9})} = e^0 \Leftrightarrow \frac{x-4}{2x-9} = 1$

$\Leftrightarrow x-4 = 2x-9 \Leftrightarrow x = 5$
• Sep 25th 2009, 07:46 AM
songoku
Hi wannous

Well, you can solve the first question so why can't you solve the second one? I got x = 5 for the second question using the same method to solve the first one :)