Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Matrices

Question:

If A satisfies the equation $x^3 -5x^2+4x+λ=0$, then $A^{-1}$ exists if

Options:

$λ≠1$

$λ≠2$

$λ≠-1$

$λ≠0$

Correct Answer:

$λ≠0$

Explanation:

Since A satisfies the equation

$x^3-5x^2+4x+λ=0$

$⇒A^3 -5A^2 + 4A + λI=0$

$⇒A (-A^2+5A-4 I) = λI$

$⇒A\left\{\frac{1}{λ}(-A^2+5A-4 I)\right\}=I$, if $λ≠0$

Hence, $A^{-1}$ exists and is equal to $\frac{1}{λ}(-A^2+5A-4 I)$ if $λ≠0$.