Step |
Hyp |
Ref |
Expression |
1 |
|
recn |
⊢ ( 𝐴 ∈ ℝ → 𝐴 ∈ ℂ ) |
2 |
|
recn |
⊢ ( 𝐵 ∈ ℝ → 𝐵 ∈ ℂ ) |
3 |
|
addcom |
⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ) → ( 𝐴 + 𝐵 ) = ( 𝐵 + 𝐴 ) ) |
4 |
1 2 3
|
syl2an |
⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ) → ( 𝐴 + 𝐵 ) = ( 𝐵 + 𝐴 ) ) |
5 |
4
|
3adant3 |
⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ ) → ( 𝐴 + 𝐵 ) = ( 𝐵 + 𝐴 ) ) |
6 |
5
|
breq1d |
⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ ) → ( ( 𝐴 + 𝐵 ) ≤ 𝐶 ↔ ( 𝐵 + 𝐴 ) ≤ 𝐶 ) ) |
7 |
|
leaddsub |
⊢ ( ( 𝐵 ∈ ℝ ∧ 𝐴 ∈ ℝ ∧ 𝐶 ∈ ℝ ) → ( ( 𝐵 + 𝐴 ) ≤ 𝐶 ↔ 𝐵 ≤ ( 𝐶 − 𝐴 ) ) ) |
8 |
7
|
3com12 |
⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ ) → ( ( 𝐵 + 𝐴 ) ≤ 𝐶 ↔ 𝐵 ≤ ( 𝐶 − 𝐴 ) ) ) |
9 |
6 8
|
bitrd |
⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐶 ∈ ℝ ) → ( ( 𝐴 + 𝐵 ) ≤ 𝐶 ↔ 𝐵 ≤ ( 𝐶 − 𝐴 ) ) ) |