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#1 2005-10-25 20:39:44
- Bboy PhysicX
- Guest
:: Log Functions ::
Hi! can you teach me how to do this thing?
I'm really confused... so please~~
THANK YOU~
Solve:
ln (x^2 + 1) = 2 ln (x + 1)
and
log (7x - 12) = 2 log x
#2 2005-10-25 20:57:23
- mathsyperson
- Moderator
Offline
Re: :: Log Functions ::
Use the identity a log b = log (b^a).
1) ln (x²+1) = 2 ln (x+1)
ln (x²+1) = ln (x+1)²
x²+1 = x²+2x+1
2x = 0
x = 0
2) log (7x-12) = 2 log x
log (7x-12) = log (x²)
7x-12 = x²
x²-7x+12 = 0
(x-4)(x-3) = 0
x = 3 or 4
Why did the vector cross the road?
It wanted to be normal.