Prove by Mathematical Induction that (A’)n = (An)’, where n ∈ N for any square matrix A.
By principle of mathematical induction we say that if a statement P(n) is true for n = 1 and if we assume P(k) to be true for some random natural number k and usnig it if we prove P(k+1) to be true we can say that P(n) is true for all natural numbers.
We are given to prove that (A’)n = (An)’.
Let P(n) be the statement : (A’)n = (An)’.
Clearly, P(1): (A’)1 = (A1)’
⇒ P(1) : A’ = A’
⇒ P(1) is true
Let P(k) be true.
∴ (A’)k = (Ak)’ …(1)
Let’s take P(k+1) now:
∵ (Ak+1)’ = (AkA)’
We know that by properties of transpose of a matrix:
(AB)T = BTAT
∴ (AkA)’ = A’(Ak)’ = A’(A’)k = (A’)k+1
Thus, (Ak+1)’ = (A’)k+1
∴ P(k+1) is true.
Hence,
We can say that: (A’)n = (An)’ is true for all n ∈ N.