Quadratic Equations · Class 10 · CBSE Mathematics

Find the value of k for which the quadratic equation kx(x - 2) + 6 = 0 has two real and equal roots.

Practice question from Quadratic Equations (Class 10 · CBSE Mathematics), with the correct answer and a step-by-step solution.

medium · MCQ · Q-F82EE7

Find the value of kk for which the quadratic equation kx(x−2)+6=0kx(x - 2) + 6 = 0 has two real and equal roots.

  1. A.00 or 66
  2. B.Only 66Correct answer
  3. C.00 or −6-6
  4. D.Only −6-6

Solution

The given equation can be written as kx2−2kx+6=0kx^2 - 2kx + 6 = 0. For real and equal roots, the discriminant D=b2−4ac=0D = b^2 - 4ac = 0. Here a=ka = k, b=−2kb = -2k, and c=6c = 6. So, (−2k)2−4(k)(6)=0  ⟹  4k2−24k=0  ⟹  4k(k−6)=0(-2k)^2 - 4(k)(6) = 0 \implies 4k^2 - 24k = 0 \implies 4k(k - 6) = 0. Since k≠0k \neq 0 for a quadratic equation, we get k=6k = 6.

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