Metamath Proof Explorer


Theorem hvsubadd

Description: Relationship between vector subtraction and addition. (Contributed by NM, 30-Oct-1999) (New usage is discouraged.)

Ref Expression
Assertion hvsubadd A B C A - B = C B + C = A

Proof

Step Hyp Ref Expression
1 oveq1 A = if A A 0 A - B = if A A 0 - B
2 1 eqeq1d A = if A A 0 A - B = C if A A 0 - B = C
3 eqeq2 A = if A A 0 B + C = A B + C = if A A 0
4 2 3 bibi12d A = if A A 0 A - B = C B + C = A if A A 0 - B = C B + C = if A A 0
5 oveq2 B = if B B 0 if A A 0 - B = if A A 0 - if B B 0
6 5 eqeq1d B = if B B 0 if A A 0 - B = C if A A 0 - if B B 0 = C
7 oveq1 B = if B B 0 B + C = if B B 0 + C
8 7 eqeq1d B = if B B 0 B + C = if A A 0 if B B 0 + C = if A A 0
9 6 8 bibi12d B = if B B 0 if A A 0 - B = C B + C = if A A 0 if A A 0 - if B B 0 = C if B B 0 + C = if A A 0
10 eqeq2 C = if C C 0 if A A 0 - if B B 0 = C if A A 0 - if B B 0 = if C C 0
11 oveq2 C = if C C 0 if B B 0 + C = if B B 0 + if C C 0
12 11 eqeq1d C = if C C 0 if B B 0 + C = if A A 0 if B B 0 + if C C 0 = if A A 0
13 10 12 bibi12d C = if C C 0 if A A 0 - if B B 0 = C if B B 0 + C = if A A 0 if A A 0 - if B B 0 = if C C 0 if B B 0 + if C C 0 = if A A 0
14 ifhvhv0 if A A 0
15 ifhvhv0 if B B 0
16 ifhvhv0 if C C 0
17 14 15 16 hvsubaddi if A A 0 - if B B 0 = if C C 0 if B B 0 + if C C 0 = if A A 0
18 4 9 13 17 dedth3h A B C A - B = C B + C = A