Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Determinants

Question:

The equations $λx – y =2, 2x – 3y = –λ, 3x – 2y = –1$ are consistent for

Options:

$λ= –4$

$λ = –1, 4$

$λ= –1$

$λ = 1, –4$

Correct Answer:

$λ = –1, 4$

Explanation:

$\begin{vmatrix}λ&-1&-2\\2&-3&λ\\3&-2&1\end{vmatrix}=0$

$⇒λ(–3 + 2λ) + 1 (2 – 3λ) – 2(–4 + 9) + 0$

$⇒ 2λ^2 – 6λ – 8 = 0 ⇒ λ^2 – 3λ – 4 = 0$

$⇒(λ – 4) (λ + 1) = 0$  $∴ λ = –1, 4$