Q14 of 82 Page 4

For what value of k does the quadratic equation

kx(x – 2) + 6 = 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 – 2kx + 6 = 0


⇒ D = 4k2 – 4 × 6 × k = 0


⇒ 4k(k – 6) = 0


⇒ k = 0, 6 but k can’t be 0 a it is the coefficient of x2, thus k = 6

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