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| Mirrors > Home > MPE Home > Th. List > ressxr | Structured version Visualization version GIF version | ||
| Description: The standard reals are a subset of the extended reals. (Contributed by NM, 14-Oct-2005.) |
| Ref | Expression |
|---|---|
| ressxr | ⊢ ℝ ⊆ ℝ* |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ssun1 4178 | . 2 ⊢ ℝ ⊆ (ℝ ∪ {+∞, -∞}) | |
| 2 | df-xr 11299 | . 2 ⊢ ℝ* = (ℝ ∪ {+∞, -∞}) | |
| 3 | 1, 2 | sseqtrri 4033 | 1 ⊢ ℝ ⊆ ℝ* |
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