Lines represented by 9 x^2+y^2+6 x y-4=0 are - Vidyadip

MCQ

Lines represented by $9 x^2+y^2+6 x y-4=0$ are

A
coincident.
✓
parallel but not coincident.
C
not parallel.
D
perpendicular.

✓

Answer

Correct option: B.

parallel but not coincident.

(B) Given equation of pair of lines is $9 x^2+y^2+6 x y-4=0$
$\therefore \quad a=9, b=1, h=3$
$h^2-a b=3^2-9(1)=0$
$\therefore \quad$ The lines are parallel
Now, $9 x^2+6 x y+y^2=4$
$\Rightarrow(3 x+y)^2=4 \Rightarrow 3 x+y= \pm 2$
Hence, the lines are parallel and not coincident.

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