eli5: why is x⁰ = 1 instead of non-existent?

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It kinda doesn’t make sense.
x¹= x

x² = x*x

x³= x*x*x

etc…

and even with negative numbers you’re still multiplying the number by itself

like (x)-² = 1/x² = 1/(x*x)

In: 1797

38 Answers

Anonymous 0 Comments

Well, a simple reason is that we want x^a times x^b to be x^(a+b).

So: x^1 is x. x^(-1) is 1/x. What is x times 1/x? It’s 1. But that’s also x^1 times x^(-1) = x^(1 + -1) = x^(0).

A somewhat more formal approach is to think of x^0 as an empty product. You’re not multiplying anything, which is the same as multiplying by 1. Or to extend your logic from the OP:

> It kinda doesn’t make sense

> x*1 = x

> x*2 = x + x

> x*3 = x + x + x

So in this case, x*0 is the empty sum, which is the same as not adding anything, which is the same as adding 0. (And of course, x * 0 is in fact 0.)

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