Questions about Zero - Undefined or Indeterminate?
From: Norman Rogers Subject: Nothing about nothing Date: Wed, 16 Aug 95 22:56:55 EDT 1/ Is 0,0,0,... a geometric sequence ? 2/ What is the value of 0/0 ? (is it really undefined or are there an infinite number of values) 3/ What is the value of 0^0 (^ means exponent)? Can it be considered to be the limit of a^0 as a approaches 0 ? Any thoughts on these would be appreciated. Thanx Norman Rogers
Date: 809188843 From: Doctor Ken Subject: Re: Nothing about nothing Hello! >1/ Is 0,0,0,... a geometric sequence ? > Well, sort of. You could say that it's a geometric sequence with common ratio 4, or whatever, but I wouldn't. The reason is that you can't find the common ratio by looking at the sequence, dividing one term by the previous term. So I guess I'd say no. What you might say is that this is a degenerate case of a geometric sequence. >2/ What is the value of 0/0 ? (is it really undefined or are there an > infinite number of values) > There's a special word for stuff like this, where you could conceivably give it any number of values. That word is "indeterminate." It's not the same as undefined. It essentially means that if it pops up somewhere, you don't know what its value will be in your case. For instance, if you have the limit as x->0 of x/x and of 7x/x, the expression will have a value of 1 in the first case and 7 in the second case. Indeterminate. >3/ What is the value of 0^0 (^ means exponent)? Can it be considered to > be the limit of a^0 as a approaches 0 ? > 0^0 is indeed indeterminate. It turns out that you could make it have any value between 0 and 1, inclusive. You could have 0 if it's the limit as a->0 of 0^a, you could have 1 if it's the limit as a->0 of a^0, and for x in between 0 and 1, (and this is the neat part from Dr. Shimimoto) look at the expression (x^n)^(1/n). This just equals x for all positive values of n. As n->Infinity, this fraction goes to 0^0, but if it's just x the whole time, the limit of the expression as it goes to 0^0 is x. So we could make it anything in between 0 and 1, so it's got to be indeterminate. -Doctor Ken, The Geometry Forum
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.