Q12 of 82 Page 4

For what value of k does the quadratic equation

kx (x – 2√5) + 10 = 0 have equal roots? (CBSE 2013)

 


For a quadratic equation, ax2 + bx + c = 0,


D = b2 – 4ac


If D = 0, roots are real and equal



⇒ kx2 – 2√5kx + 10 = 0


⇒ D = 4 × 5k2 – 4 × k × 10 = 0


⇒ k2 = 2k


⇒ k = 2

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