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Find the values of k for which the following equations have real roots
$kx(x-2) + 6 = 0$
Given:
Given quadratic equation is $kx(x-2)+6= 0$.
To do:
We have to find the values of k for which the roots are real.
Solution:
$kx(x-2)+6=0$
$kx^2-2kx+6=0$
Comparing the given quadratic equation with the standard form of the quadratic equation $ax^2+bx+c=0$, we get,
$a=k, b=-2k$ and $c=6$.
The discriminant of the standard form of the quadratic equation $ax^2+bx+c=0$ is $D=b^2-4ac$.
$D=(-2k)^2-4(k)(6)$
$D=4k^2-24k$
The given quadratic equation has real roots if $D≥0$.
Therefore,
$4k^2-24k≥0$
$4k(k-6)≥0$
$4k≥0$ and $k-6≥0$
$k≥0$ and $k≥6$
This implies,
$k≥6$
The value of k is greater than or equal to 6.
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