Question

If A is an invertible matrix of order 2, then det (A⁻¹) is equal to
(A) det (A)
(B)$\frac{1}{det (A)}$
(C) 1
(D) 0

Answer 1

1/det(A)

Proof
A . A-1 = Identity
take determinent on both sides
det A . det A-1 = 1
det A-1 = 1/det A