Let A = [a_ij]_4×3

So, the elements in a 4×3 matrix are

a₁₁, a₁₂, a₁₃, a₂₁, a₂₂, a₂₃,a_31,a_32,a_33,a_41, a_42, a₄₃

A = ……(1)

a₁₁ = 1

a₁₂ = 1

a₁₃ = 1

a₂₁ = 2

a₂₂ = 2

a₂₃ = 2

a₃₁ = 3

a₃₂ = 3

a₃₃ = 3

a₄₁ = 4

a₄₂ = 4

a₄₃ = 4

So, from (1)

A =