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If the pairs of line represented by the equation (ax^2+2hxy+by^2+2gx+2fy+c=0) intersect each other on y axis which is not origin then which of following is/are true (a) g^2=ac (b) f^2=bc (c) 2fgh=bg^2+ch^2 (d) hc=gf

If the pairs of line represented by the equation (ax^2+2hxy+by^2+2gx+2fy+c=0) intersect each other on y axis which is not origin then which of following is/are true 
(a)  g^2=ac
(b)  f^2=bc
(c)  2fgh=bg^2+ch^2
(d)  hc=gf 

Grade:11

1 Answers

Nishant Vora IIT Patna
askIITians Faculty 2467 Points
7 years ago
the condition for this eqn to be a pair of sl is
223-2443_Capture.PNG…...............(1)
now both the straight line is intersecting on y axis
so x= 0

Put x= 0 inax^2+2hxy+by^2+2gx+2fy+c=0

soby^2 +2fy+c=0

Now for this Quadratic y1 = y2 as there is a unique point

So D=0

So4f^2 - 4bc = 0

Hence,f^2 - bc = 0

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