Raising Sides of an Equation to the 0 PowerDate: 12/04/97 at 18:53:35 From: Mr. LaVergne's 6th Hour Algebra 2H class Subject: Raising sides of an equation to the 0 power If you raise both sides of an equation to the 0 power, will both sides then be equal to one? You could make three to 0 power equal to ten to the 0 power if this is true. Please enlighten us. Date: 12/16/97 at 12:06:21 From: Doctor Mark Subject: Re: Raising sides of an equation to the 0 power Hello, 2H Sure... The short answer to your question is, yes. The longer answer to your question is.... This is not really any different from a number of other things you could do: You could multiply both sides of an equation by 0 You could divide both sides of an equation by 0. But then there are two questions I would ask you: 1. Why would you bother? 2. What would you do with the result? Let me explain... Suppose we take some equation, say a *false* one like 1 = 2. Let's multiply both sides of this false equation by 0. Then we get: 1 x 0 = 2 x 0 -------> 0 = 0. Well, that's true isn't it? But so what? The fact that we *got* a true equation when we multiplied both sides of the equation by 0 doesn't mean that the original equation was true, right? I mean, we know that 1 is not equal to 2! Okay, you say, but what if we divide both sides of the false equation 1 = 2 by 0. Well, you know what happens, right? You can't divide by 0, so our false equation becomes one meaningless quantity = another meaningless quantity. What are we going to do with that? It's not true, nor is it false, since it has no meaning. So what happens if we take the 0 power of both sides of the false equation 1 = 2? We get: 1^0 = 2^0 ----------> 1 = 1. Well, that's true, but again, so what? The fact that if you get something true by doing something to the original equation doesn't make the original equation any truer than it was (or wasn't) originally. So the real point here is this: You *can* multiply both sides by 0, or divide both sides by 0, or take the 0 power of both sides, but the result of doing any of those things tells you *absolutely nothing* about the original equation. So why bother? Aha, you say: but what if I take an equation like 3x = 6. If I divide both sides by 3, I get x = 2. If I want that to be true, x better be (ahem!) 2, so that tells me that the original equation must be true for x being 2 also. Why does the fact that x = 2 being true for x taking the value "2" tell me that x taking the value "2" also makes the *original* equation (3x = 6) true? Didn't I say earlier that when you multiply both sides by 0 to get 0 = 0 (the equation I *got*), which is a true equation, that didn't mean that the *original* equation was true? So why does x = 2 (the equation I *got* when I divided by 3) being true mean that the *original* equation (3x = 6) is true? Aren't the two situations the same? No, they aren't. And here is why. When you divide the original equation by 3 to get x = 2, that is a *reversible* step: You could multiply both sides by 3 (the number you divided by) to get 3x = 6, the original equation, so if x = 2 is true, then 3x = 6 is true. When you multiply both sides by 0,to get 0 = 0, that is *not* a reversible step, since to reverse the step, you would have to *divide* both sides of the equation 0 = 0 by 0, and that's a Big No No. You don't get *anything*. In particular, you don't get 1 = 2! Similarly, if you were to divide both sides of the equation by 0, that is also not a reversible step, since to reverse it, you would have to multiply both sides by 0. That seems like it might be okay, but it isn't, since you *don't have anything to multiply by 0*, because (in the equation you got after you divided both sides by 0) both sides are meaningless. A similar argument holds for taking the 0 power of both sides of the equation; it's not reversible, since to reverse it, you would have to take the 0th *root* of both sides of 1 = 1, and what is meant by "taking the 0th root"? [Here's the analogy: If you square both sides of an equation, you "undo" that by taking the square root: that's the basis of solving a quadratic equation by completing the square, for example. If you cube both sides of an equation, you undo that by taking the cube root of both sides. So if you take the 0 power of both sides of an equation, you would have to undo that by taking the 0th root.] A really good question, 2H, and I am glad you asked it. I hope what I have said helps... -Doctor Mark, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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