AP EAMCET2011MathematicsStraight Lines
If a x^2+2 h x y+b y^2+2 g x+2 f y+c=0 represents a pair of parallel lines, then g^2-a c f^2-b c , is equal to
Options
- Aa b
- Ba b
- Cb a
- Db a
Correct answer
B. a b
Step-by-step solution
If a x^2+2 h x y+b y^2+2 g x+2 f y+c=0 represents a pair of parallel lines, then g^2-a c a(a+b) = f^2-b c b(a+b) g^2-a c f^2-b c = a b