A={1,2,3,4,5,6,7,8}
B={0,1,2,3,4,5,6,7,8,9}
C={1,2,3}
a)A U B={1,2,3,4,5,6,7,8,0,9}
b)A U C={1,2,3,4,5,6,7,8}
c)B U C={0,1,2,3,4,5,6,7,8,9}
d)A (nu pot face semnul) B={1,2,3,4,5,6,7,8}
e)A (nu pot face semnul) C={1,2,3}
f)B (nu pot face semnul) C={1,2,3}
g)A (nu pot face semnul)B(nu pot face semnul)C={1,2,3}
h)C U (A(nu pot face semnul)B)={1,2,3,4,5,6,7,8}
gata!