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Question

Mathematics Question on Parabola

If 2x+3y+12=02x + 3y + 12 = 0 and xy+4λ=0x - y + 4 \lambda = 0 are conjugate with respect to the parabola y2=8xy^2 = 8x, then λ\lambda is equal to

A

2

B

-2

C

3

D

-3

Answer

-3

Explanation

Solution

If 2x+3y+12=02 x +3 y +12=0 and xy+4λ=0x - y +4 \lambda=0
are conjugate with respect to parabola y2=8xy ^{2}=8 x then λ\lambda is equal to :
11x+m1y+n1=01_{1} x +m_{1} y+ n_{1}=0
l2x+m2y+n2=0l _{2} x + m _{2} y + n _{2}=0
Are conjugate with respect to parabola y2=4axy ^{2}=4 ax
lln2+l2n1=2am1m2l _{ l } n _{2}+ l _{2} n _{1}=2 am _{1} m _{2}
8λ+12=128 \lambda+12=-12
λ=3\lambda=-3