Description: If two pairs of numbers are componentwise congruent, so are their differences. (Contributed by Stefan O'Rear, 2-Oct-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | congsub | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simp11 | |
|
2 | simp12 | |
|
3 | simp13 | |
|
4 | simp2l | |
|
5 | 4 | znegcld | |
6 | simp2r | |
|
7 | 6 | znegcld | |
8 | simp3l | |
|
9 | simp3r | |
|
10 | congneg | |
|
11 | 1 4 6 9 10 | syl22anc | |
12 | congadd | |
|
13 | 1 2 3 5 7 8 11 12 | syl322anc | |
14 | 2 | zcnd | |
15 | 4 | zcnd | |
16 | 14 15 | negsubd | |
17 | 3 | zcnd | |
18 | 6 | zcnd | |
19 | 17 18 | negsubd | |
20 | 16 19 | oveq12d | |
21 | 13 20 | breqtrd | |