MHT CET202520 Apr 2025Morning ShiftMathematicsPair of LinesActual
The distance between the lines represented by the equation 4 x^2+4 x y+y^2-6 x-3 y-4=0 is
Options
- A1 5 units
- B1 5 units
- C5 units
- D5 units
Correct answer
C. 5 units
Step-by-step solution
The quadratic 4x^2 + 4xy + y^2 is a perfect square, factoring as (2x + y)^2 . This substitution reduces the original equation 4x^2 + 4xy + y^2 - 6x - 3y - 4 = 0 to (2x + y)^2 - 3(2x + y) - 4 = 0 . Letting Y = 2x + y gives the quadratic Y^2 - 3Y - 4 = 0 , which factors as (Y - 4)(Y + 1) = 0 . The solutions are Y = 4 and Y = -1 . Substituting back produces the two parallel lines: 2x + y - 4 = 0 2x + y + 1 = 0 The distance between parallel lines of the form Ax + By + C₁ = 0 and Ax + By + C₂ = 0 is given by d = |C₁ - C