If a and b positive numbers (a < b), then the range of values of k for which a real λ be found such that equation ax2+2λxy+by2+2k(x+y+1)=0 represents a pair of straight lines is

Book Online Demo

Check Your IQ

Try Test

Courses

Dropper NEET Course Dropper JEE Course Class - 12 NEET Course Class - 12 JEE Course Class - 11 NEET Course Class - 11 JEE Course Class - 10 Foundation NEET Course Class - 10 Foundation JEE Course Class - 10 CBSE Course Class - 9 Foundation NEET Course Class - 9 Foundation JEE Course Class -9 CBSE Course Class - 8 CBSE Course Class - 7 CBSE Course Class - 6 CBSE Course

Offline Centres

If a and b positive numbers (a < b), then the range of values of k for which a real $λ$ be found such that equation ${ax}^{2} + 2 λxy + {by}^{2} + 2 k (x + y + 1) = 0$ represents a pair of straight lines is

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

$a \leq k^{2} \leq b$

$k^{2} \leq a or k^{2} \geq b$

$a < k^{2} < b$

$k \leq 2 a or k \geq 2 b$

answer is D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

$We have h = λ, g = k, c = 2 k; f = k$
$\begin{array}{l} (a) (b) (2 k) + 2 (k) (k) (λ) - a (k)^{2} - b (k^{2}) - 2 {kλ}^{2} = 0 \\ \Rightarrow 2 abk + 2 k^{2} λ - {ak}^{2} - {bk}^{2} - 2 {kλ}^{2} = 0 \\ \Rightarrow b^{2} - 4 ac \geq 0 \Rightarrow b = 2 k^{2}, a = 2 k \\ \Rightarrow c = {ak}^{2} + {bk}^{2} - 2 abk \\ \Rightarrow 4 k^{4} - (4) (2 k) ({ak}^{2} + {bk}^{2} - 2 abk) \geq 0 \\ \Rightarrow (k - 2 a) (k - 2 b) \geq 0 \Rightarrow 2 a \leq k or k \geq 2 b \end{array}$