Which of the following sets are null sets? (i) A = {x/x^2 = 16 and 2x =4} (ii) B = {x/x + 6 =6}

 Which of the following sets are null sets?  

(i)  A = {x/x2 = 16 and 2x =4}      

(ii)  B = {x/x + 6 =6}

Solution:

A = {x/x2 = 16 and 2x =4}

x2 = 16 are 2x = 4

        x = 2

or    22 = 16 (put x = 2)

            4 ≠ 16

therefore A is null set

(ii) B = {x/x + 6 = 6}

        x + 6 = 6

        x = 0

    B = {0}  B is not a null set.