Proofs: Fill in the blank with the best selection.
ents
1. (A) -(B•C))
2. (A•C)
[:~B
asm for RA
3. --B
4.1
3 NN
5. A
6.-(
BC)
1,5 IF-THEN
7.
4,6 NOT-BOTH
8. C
2 AND
9..
3-8 RA (7 contradicts 8)
What is the missing formula on line 4?
oard
cral
(AB)
(
BC)
В
O -B