Question
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 = – k1 (A2 – 5A + 5I)
\ A–1 exists if k ¹ 0