Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE MainMathematicsStraight Lines

If the lines represented by the equation 4xy + y^2 - 4x - 2y + 1 = 0 and the line kx + (k-1)y - 2 = 0 do not form a triangle, and P is the sum of squares of all possible real values of k , then the value of 9P is ________.

Correct answer

97

Step-by-step solution

The given second-degree equation is 4xy + y^2 - 4x - 2y + 1 = 0 . This can be rewritten as: y^2 - 2y + 1 + 4x(y - 1) = 0 (y - 1)^2 + 4x(y - 1) = 0 (y - 1)(4x + y - 1) = 0 Thus, the two lines are L₁: y = 1 and L₂: 4x + y = 1 . Solving these, their point of intersection is (0, 1) . The third line is L₃: kx + (k-1)y - 2 = 0 . For the three lines to not form a triangle, L₃ must either be concurrent with L₁ and L₂ , or parallel to one of them. Case 1: Concurrency L₃ passes through (0, 1) : k(0) + (k-1)(1) - 2 = 0 k = 3

Practice Straight Lines on Quantrex Academy →

More from Straight Lines

If a straight line drawn through the point of intersection of the lines 4x+3y-1=0 and 3x+4y-1=0 , meets the co-ordinate axes at the points P and Q, then the locus of the mid point 2026From the point (-1, -1) , two rays are sent making angles of 45° with the line x + y = 0 . These rays get reflected from the mirror x + 2y = 1 . If the equations of the reflected r 2026In an equilateral triangle PQR , let the vertex P be at (3, 5) and the side QR be along the line x + y = 4 . If the orthocentre of the triangle PQR is ( , ) , then 9( + ) is equal 2026Let P(3 , 2 ) , 0 , be a point on the ellipse x^2 9 + y^2 4 =1 , Q be a point on the circle x^2+y^2-14x-14y+82=0 and R be a point on the line x+y=5 such that the centroid of the tr 2026Let A,B be points on the two half-lines x- 3 |y|= , >0 at a distance of from their point of intersection P . The line segment AB meets the angle bisector of the given half-lines at 2026Let the line L₁ : x + 3 = 0 intersect the lines L₂ : x - y = 0 and L₃ : 3x + y = 0 at the points A and B , respectively. Let the bisector of the obtuse angle between the lines L₂ a 2026Let the vertex A of a triangle ABC be (1, 2) , and the mid-point of the side AB be (5, -1) . If the centroid of this triangle is (3, 4) and its circumcenter is ( , ) , then 21( + ) 2026Let the mid points of the sides of a triangle ABC be ( 5 2 , 7 ) , ( 5 2 , 3 ) and (4, 5) . If its incentre is (h, k) , then 3h + k is equal to : 2026 Full Straight Lines list All JEE Main PYQs