Question

For A = `[(3,1),(-1,2)]`, then 14A⁻¹ is given by:

Options

• `14[(2,-1),(1,3)]`

• `[(4,-2),(2,6)]`

• `2[(2,-1),(1,-3)]`

• `2[(-3,-1),(1,-2)]`

Answer 1

`[(4,-2),(2,6)]`

Explanation:

|A| = 7, adj A = `[(2,-1),(1,3)]`

∴ 14A⁻¹ = `14 xx 1/7 [(2,-1),(1,3)]`

= `[(4,-2),(2,6)]`