# If – 5 is a root of the quadratic equation 2x2 + px – 15 = 0 and the quadratic equation p (x2 + x) + k = 0 has equal roots, find the value of k.

Given that – 5 is a root of the quadratic equation 2x2 + px – 15 = 0

2(– 5)2 – 5p – 15 = 0

5p = 35

p = 7

Given equation is p (x2 + x) + k = 0

px2 + px + k = 0

Comparing with standard quadratic equation ax2 + bx + c = 0

a = p b = p c = k

Given that the roots of equation are equal

Thus D = 0

Discriminant D = b2 – 4ac = 0

[p]2 – 4.p.k = 0

72 – 28k = 0

49 – 28k = 0

The value of k is for which roots of the quadratic equation are equal.

Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Quiz | Knowing the Nature of Roots44 mins
Take a Dip Into Quadratic graphs32 mins
Foundation | Practice Important Questions for Foundation54 mins
Nature of Roots of Quadratic EquationsFREE Class
Getting Familiar with Nature of Roots of Quadratic Equations51 mins
Quadratic Equation: Previous Year NTSE Questions32 mins
Champ Quiz | Quadratic Equation33 mins
Balance the Chemical Equations49 mins
Champ Quiz | Quadratic Equation48 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses