8) U = {1, 2, 3, 4, 5, 6} A = {2, 3, 6}
c) A' = {1, 4, 5} ---> A ^A' = {2, 3, 6} ^ {1, 4, 5} = { } (the null set)
d) U' = { } ---> U' ^ A = { } ^ {2, 3, 6} = { }
9) P = {1, 3, 5, 7} Q = {3, 7, 9, 11} R = {1, 5, 8, 11}
a) Show that: P v Q = Q V P
---> Since P v Q = {1, 3, 5, 7} v {3, 7, 9, 11} = {1, 3, 4, 7, 9, 11}
---> and Q v P = {3, 7, 9, 11} v {1, 3, 5,7 } = {1, 3, 4, 7, 9, 11},
therefore P v Q = Q v P
b) Show that: (P v Q) v R = P v (Q v R)
---> Since (P v Q) v R = ( {1, 3, 5, 7} v {3, 7, 9, 11} ) v {1, 5, 8, 11}
= {1, 3, 5, 7, 9, 11} v {1, 5, 8, 11} = {1, 3, 5, 7, 8, 9, 11}
---> and P v (Q v R) = {1, 3, 5, 7} v ( {3, 7, 9, 11} v {1, 5, 8, 11} )
= {1, 3, 5, 7} v {1, 3, 5, 7, 8, 9, 11} = {1, 3, 5, 7, 8, 9, 11}
therefore (P v Q) v R = P v (Q v R)
c) Show that: P ^ Q = Q ^ P
---> Since P ^ Q = {1, 3, 5, 7} ^ {3, 7, 9, 11} = {3, 7}
---> and Q ^ P = {3, 7, 9, 11| ^ {1, 3, 5, 7} = {3, 7}
therefore P ^ Q = Q ^ P
d) Show that: (P ^ Q) ^ R = P ^ (Q ^ R)
---> Since (P ^ Q) ^ R = ( {1, 3, 5, 7} ^ {3, 7, 9, 11} ) ^ {1, 5, 8, 11}
= {3, 7} ^ {1, 5, 8, 11} = { }
and P ^ (Q ^ R) = {1, 3, 5, 7} ^ ( {3, 7, 9, 11} ^ {1, 5, 8, 11} )
= {1, 3, 5, 7} ^ { } = { }
therefore (P ^ Q) ^ R = P ^ (Q ^ R)
e) Show that P v (Q ^ R) = (P v Q) ^ (P v R)
---> Since P v (Q ^ R) = {1, 3, 5, 7} v ( {3, 7, 9, 11} ^ {1, 5, 8, 11} )
= {1, 3, 5, 7} v { 11 } = {1, 3, 5, 7, 11}
and (P v Q) ^ (P v R) = ( {1, 3, 5, 7} v {3, 7, 9, 11} ) ^ ( { 1, 3, 5, 7} v {1, 5, 8, 11} )
= {1, 3, 5, 7, 9, 11} ^ {1, 3, 5, 7, 8, 11} = {1, 3, 5, 7, 11}
therefore P v (Q ^ R) = (P v Q) ^ (P v R)
f) Show that P ^ (Q v R) = (P ^ Q) v (P ^ R)
---> Since P ^ (Q v R) = {1, 3, 5, 7} ^ ( {3, 7. 9. 11} v {1, 5, 8, 11} )
= {1, 3, 5, 7} ^ {1, 3, 5, 7, 8, 9, 11} = {1, 3, 5, 7 }
and (P ^ Q) v (P ^ R) = ( {1, 3, 5, 7} ^ (3, 7, 9, 11} ) v ( {1, 3, 5, 7} ^ {1, 5, 8, 11} )
= {3, 7} v {1, 5} = {1, 3, 5, 7}