Construct a 3 x 4 matrix whose elements are
a_{i  j} = i –J

Let A = [ a_ii] be required 3 x 4 matrix where a_ij= i - j
a₁₁ = 1 - 1 = 0, a₁₂ =1 - 2= - 1, a₁₃=1 - 3 = - 2, a₁₄ = 1 - 4 = -3
      a₂₁ = 2 - 1 = 1, a₂₂ =2 - 2= 0, a₂₃=2 - 3 = -1, a₂₄ = 2 - 4 = - 2
      a₃₁ = 3 - 1 = 2, a₃₂ =3 - 2, a₃₃=3 - 3 = 0, a₃₄ = 3 - 4 = - 1