Logarithm

Why is the value of log-3-27 ≠3?
Because... log-3-27 = log-3(-3 * 9)=log-3-3 + log-39 = 1 + 2 = 3

7 Answers

1357
Manish Shankar ·

@Anurag

logax=N

then we have aN=x

which we define only when a is positive and not equal to 1.

(a)N will remain positive for all value of N.

so x will remain positive.

and so x is greater than 0

262
Aditya Bhutra ·

logarithm is not defined for non positive numbers.

45
Raunaq Saha ·

LOG IS NOT DEFINED FOR NEGATIVE BASES

11
Neelarun Mukherjee ·

why we cant define aN=x,when a is +ve?
-3*-3*-3=-27
(-3)3=-27.

1
abhasup1 ·

SEE...
log-3(-27) can be written as loge(-27)/loge(-3)...now
lets take loge(-27)=y
then ey=-27,now we all know that e is a positive quantity(with value 2.71828)now its power can never yield a negative result therefore loga(variable) is only defined for var>0 && a>0...

11
Ashish Tiwari ·

If the base of a log is -ve it's value cannot be determined !!!!

21
Arnab Kundu ·

Sir, we can have values like
\log z=\log|z|+i\arg(z)

So, why cannot we have values for negative reals?
The answer might not be in reals but we can have.

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