Question

If A,B are disjoint sets andA_B=(1,2,3),B_A=(6,7,8,9)then find the sets A,B

Answer 1

given a-b = (1,2,3) i.e.,
        a=(1,2,3) and
         b-a= (6,7,8,9)
         i.e., b=(6,7,8,9)

Answer 2

Since A and B are dis-joint sets so they have no element in common 

so A - B = {1,2,3} which gives A = {1,2,3}

and B - A = {6,7,8,9}  which gives B = {6,7,8,9}