deriving a negative logarithm of a fraction

[kmax]

Hi all,

Can you convert:
-In(1/2) = In2

can you cancel the negative by flipping the fraction?

Thanks
Keir

 

[Deleted member 4993]

Hi all,

Can you convert:
-In(1/2) = In2

can you cancel the negative by flipping the fraction?

Thanks
Keir

Use:

1/2 = 2^(-1) .... or... 2^-1.............. and

ln[a^m] = m * ln(a)

 

[Steven G]

Use:

1/2 = 2^(-1) .... or... 2^-1.............. and

ln[a^m] = m * ln(a) ONLY if a >0.

For example since 4 = (-2)^2, we can say that ln(4) = ln[ (-2)^2 ] but we can't say that ln[ (-2)^2 ] = 2ln(-2). Why? Because you can't have ln( a non-positive number).

Having said that you may use Prof Khan's method because you will NOT be taking the ln of a non-positive number.