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Question: If A satisfies the equation x<sup>3</sup> – 5x<sup>2</sup> + 4x + k = 0, then A<sup>–1</sup> exists ...

If A satisfies the equation x3 – 5x2 + 4x + k = 0, then A–1 exists if –

A

k¹ 1

B

k ¹ 3

C

k ¹ – 1

D

None

Answer

None

Explanation

Solution

A3 – 5A2 + 5A+ k.I = 0

A–1 (A3 – 5A2 + 5A + kI) = A–1 × (0)

A2 – 5A + 5I + kA–1 = 0

A–1 = – 1k\frac{1}{k} (A2 – 5A + 5I)

\ A–1 exists if k ¹ 0