Question

( f )
[
9 x^{2}+6 y^{2}+2 n x y+28 x+2 f y+c=0 text { is }
]
a pair of lines them
[
begin{array}{c}
a b c+2 n+g-a f^{2}-b g^{2}-c n^{2}=0
a=a quad g=2
end{array}
]
so here
[
begin{array}{l}
b=-1 quad f=-frac{1}{2}
h=0
end{array}
]
Put values in
[
begin{array}{c}
-aleft(frac{1}{4}right)+4=0
a=16
end{array}
]

# If ax -y + 4x -y=0 represents a pair of lines, then a is equal to : (a) - 16 (b) 16 (c) 4 (d) – 4

Solution