Description: 3 is less than 9. (Contributed by Mario Carneiro, 9-Mar-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | 3lt9 | ⊢ 3 < 9 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3lt4 | ⊢ 3 < 4 | |
2 | 4lt9 | ⊢ 4 < 9 | |
3 | 3re | ⊢ 3 ∈ ℝ | |
4 | 4re | ⊢ 4 ∈ ℝ | |
5 | 9re | ⊢ 9 ∈ ℝ | |
6 | 3 4 5 | lttri | ⊢ ( ( 3 < 4 ∧ 4 < 9 ) → 3 < 9 ) |
7 | 1 2 6 | mp2an | ⊢ 3 < 9 |