Question

Tolong ya no 3 nomor.......

Answer 1

N ( a U b ) = n ( A ) +  n ( B ) - n ( a U b )
b = ( a + b ) + ( b + c ) - ( a + b + c )
b = a + b + b + c - a - b - c
b = b

Answer 2

N (AUB) = a + b + c
n (AUB) =n(A) + n(B) - n (AuB)
             = a + b + b + c - b
             = a + b + c------> terbukti