Write down all the subsets of the following sets

(i) {a} (ii) {a, b} (iii) {1, 2, 3} (iv) φ

(a) A   =  {a}

Number of elements in set A = 1
  Number of subsets = 2¹ = 2

∴ The subsets are  φ, {a}

(b)      A   =  {a, b}
Number of elements in set A = 2

  Number of subsets = 2² = 4

∴ The subsets are  φ, {a}, {b}, {a, b}

(c)  A   =  {1, 2, 3}
Number of elements in set A = 3

 Number of subsets = 2³ = 8

∴ The subsets are  φ, {1}, {2}, {3}, {1, 2}, {2, 3}, {1, 3} and {1, 2, 3}

(d)   φ  = {  }
Number of elements  = 0
  Number of subsets = 2⁰ = 1
∴ The subsets is φ