Logarithmic Equation

**thebristolsound** · November 12th 2009, 10:54 AM

Logarithmic equation, missed lecture this day. I just need to know how you go about solving these problems. Thank you so much!

ln(x+5)+ln(x−5)=0

**e^(i*pi)** · November 12th 2009, 11:10 AM

Originally Posted by thebristolsound

Logarithmic equation, missed lecture this day. I just need to know how you go about solving these problems. Thank you so much!

ln(x+5)+ln(x−5)=0

$ln(a)+ln(b) = ln(ab)$

$<br /> ln[(x+5)(x-5)] = 0$

**thebristolsound** · November 12th 2009, 11:31 AM

so from (x+5)(x-5) would I then make the other side e^0 giving me 1?

Does (x+5)(x-5) become x^2-25?

**e^(i*pi)** · November 12th 2009, 11:54 AM

Originally Posted by thebristolsound

so from (x+5)(x-5) would I then make the other side e^0 giving me 1?

Does (x+5)(x-5) become x^2-25?

Yes and Yes (it's the difference of two squares) so you get $x^2-26=0$ . As 26 is 2*13 it will no break down to be simpler than $\sqrt{26}$

Thread: Logarithmic Equation