Proof: Negative Exponent

Let's prove the following theorem:

if not (xm = 0), then x((-1) ⋅ m) = 1 / (xm)

Power to a negative number is 1 divided by the power to the inverse of the number. For example, 2-3 = 1 / 23

Proof:

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Given
1 not (xm = 0)
Proof Table
# Claim Reason
1 x(m + ((-1) ⋅ m)) = (xm) ⋅ (x((-1) ⋅ m)) x(m + ((-1) ⋅ m)) = (xm) ⋅ (x((-1) ⋅ m))
2 m + ((-1) ⋅ m) = 0 m + ((-1) ⋅ m) = 0
3 x(m + ((-1) ⋅ m)) = x0 if m + ((-1) ⋅ m) = 0, then x(m + ((-1) ⋅ m)) = x0
4 x0 = 1 x0 = 1
5 x(m + ((-1) ⋅ m)) = 1 if x(m + ((-1) ⋅ m)) = x0 and x0 = 1, then x(m + ((-1) ⋅ m)) = 1
6 1 = (xm) ⋅ (x((-1) ⋅ m)) if x(m + ((-1) ⋅ m)) = 1 and x(m + ((-1) ⋅ m)) = (xm) ⋅ (x((-1) ⋅ m)), then 1 = (xm) ⋅ (x((-1) ⋅ m))
7 x((-1) ⋅ m) = 1 / (xm) if 1 = (xm) ⋅ (x((-1) ⋅ m)) and not (xm = 0), then x((-1) ⋅ m) = 1 / (xm)
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