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:
Given
| 1 | not (xm = 0) |
|---|
| # | 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 x0 = 1 and x(m + ((-1) ⋅ m)) = x0, then x(m + ((-1) ⋅ m)) = 1 |
| 6 | 1 = (xm) ⋅ (x((-1) ⋅ m)) | if x(m + ((-1) ⋅ m)) = (xm) ⋅ (x((-1) ⋅ m)) and x(m + ((-1) ⋅ m)) = 1, then 1 = (xm) ⋅ (x((-1) ⋅ m)) |
| 7 | x((-1) ⋅ m) = 1 / (xm) | if not (xm = 0) and 1 = (xm) ⋅ (x((-1) ⋅ m)), then x((-1) ⋅ m) = 1 / (xm) |
Comments
Please log in to add comments