Q16 of 180 Page 5

For what value of

We know that, in a quadratic equation, ax2 + bx + c = 0.


For real and equal roots, b2 – 4ac = 0


Given Equation: 2x2 – (2k + 1)x + k = 0


So, we have, a = 2, b = -(2k + 1), and c = k


Therefore,


{-(2k + 1)}2 – 4 × 2 × k = 0


4k2 + 1 + 4k – 8k = 0


4k2 – 4k + 1 = 0


This is a formula for (2k – 1)2, so,


(2k – 1)2 = 0


2k – 1 = 0


k = 1/2


Hence, for k = 1/2 the given quadratic equation has real and equal roots.


OR


Given: f(x) = 2kx2 – x + k


If x = 1, is a root of the equation, it will satisfy the equation. Therefore,


f(1) = 0


2k(1)2 – 1 + k = 0


2k – 1 + k = 0


3k – 1 = 0


k = 1/3


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