Are logarithms only non-negative?

[mileena]

I read that log_b x exists only when x >= 0

what about log_-3 -27 though?

The answer should be the exponent 3, right?

Thanks!

 

[micromass]

You can define the logarithm for all nonzero real numbers. But this requires complex number theory. So it's not suitable for high school.

 

[mileena]

You can define the logarithm for all nonzero real numbers. But this requires complex number theory. So it's not suitable for high school.

Thanks, I read the above though in the book Pre-Calculus for Dummies. It said all logarithms and bases were non-negative. I'm not that good on trigonometry or pre-calc.

 

[micromass]

Thanks, I read the above though in the book Pre-Calculus for Dummies. It said all logarithms and bases were non-negative. I'm not that good on trigonometry or pre-calc.

Yeah. So for now just take it as given that the bases are nonnegative. You might see the more general theory later.

 

[mileena]

Thank you. I will take your advice. Any less work for me is a good thing!