NCERT Solutions Class 12th Maths Chapter 3 – Matrices Exercise 3.4

June 28, 2022

?Chapter – 3?

✍Matrices✍

?Exercise 3.4?

Given, $A = [1/2 -1/3]$

Then

∣ A ∣ = ∣ ∣ ∣ ∣ ∣ ∣ 12 -13 ∣ ∣ ∣ ∣ ∣ ∣ = 3 + 2

∣ A ∣ = 5 \neq = 0

So,

A^{-1}

exists.

On finding adjoint of

A

F_{11} = 3, F_{12} = - 2, F_{21} = 1, F_{22} = 1

Matrix formed by adjoint

A

B = [31 -21]

A d j . A = B^{t} = [31 -21]^{T}

= [3-2 11]

∴ A^{-1} = ∣ A ∣ a d j . A

Hence,

A^{-1} = 51 [3-2 11]