Question

If y-intercept of plane (x – y + z – 1) + λ(x + y – z – 1) = 0 is 3 unit then λ = ____

(A) – 2

(B) 2

(C) (1/2)

(D) – (1/2)

Answer 1

The correct option (B) 2  

Explanation:

plane: (x – y + z – 1) + λ(x + y – z – 1) = 0

∴ (1 + λ)x + (λ – 1)y + (1 – λ)z – 1 – λ = 0

∴ (x/1) + [y/{– [(1 + λ) / (1 – λ)]}] + [z/{(1 + λ)/(1 – λ)}] = 1

∴ y-intercept = – [(1 + λ) / (1 – λ)] = 3

∴ – 1 – λ = 3 – 3λ

∴ λ = 2.