If $[\sqrt{n^2 +λ}=[\sqrt{n^2 +1}]+2$, where $λ,\, n∈N$ then λ can assume
Answer & explanation
Correct answer: option 3
We have,
$[\sqrt{n^2 +1}]=n$
$∴[\sqrt{n^2 +λ}=[\sqrt{n^2 +1}]+2$
$⇒[\sqrt{n^2 +λ}]=n+2$
$⇒n+2≤\sqrt{n^2 +λ} <n+3$
$⇒(n+ 2)^2 ≤n^2 +λ<(n+3)^2$
$⇒4n+4≤λ<6n+9$
$⇒λ=4n+4, 4n+5,...., 6n+ 8$.
Hence, λ can assume $(2n+5)$ distinct values.