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Find the values of k for which the following equations have real roots
$x^2 - 4kx + k = 0$
Given:
Given quadratic equation is $x^2-4kx+k=0$.
To do:
We have to find the values of k for which the roots are real.
Solution:
$x^2-4kx+k=0$
Comparing the given quadratic equation with the standard form of the quadratic equation $ax^2+bx+c=0$, we get,
$a=1, b=-4k$ and $c=k$.
The discriminant of the standard form of the quadratic equation $ax^2+bx+c=0$ is $D=b^2-4ac$.
$D=(-4k)^2-4(1)(k)$
$D=16k^2-4k$
The given quadratic equation has real roots if $D≥0$.
Therefore,
$16k^2-4k≥0$
$4k(4k-1)≥0$
$4k≥0$ and $4k-1≥0$
$k≥0$ and $4k≥1$
$k≥0$ and $k≥\frac{1}{4}$
This implies,
$k≥\frac{1}{4}$
The value of k is greater than or equal to $\frac{1}{4}$.
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