Description: Any real number subtracted from itself forms a left additive identity. (Contributed by Steven Nguyen, 8-Jan-2023)
Ref | Expression | ||
---|---|---|---|
Assertion | resubidaddid1 | ⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ) → ( ( 𝐴 −ℝ 𝐴 ) + 𝐵 ) = 𝐵 ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | readdsub | ⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ∧ 𝐴 ∈ ℝ ) → ( ( 𝐴 + 𝐵 ) −ℝ 𝐴 ) = ( ( 𝐴 −ℝ 𝐴 ) + 𝐵 ) ) | |
2 | 1 | 3anidm13 | ⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ) → ( ( 𝐴 + 𝐵 ) −ℝ 𝐴 ) = ( ( 𝐴 −ℝ 𝐴 ) + 𝐵 ) ) |
3 | repncan2 | ⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ) → ( ( 𝐴 + 𝐵 ) −ℝ 𝐴 ) = 𝐵 ) | |
4 | 2 3 | eqtr3d | ⊢ ( ( 𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ ) → ( ( 𝐴 −ℝ 𝐴 ) + 𝐵 ) = 𝐵 ) |