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Question
Write the value of k for which the quadratic equation x2 − kx + 4 = 0 has equal roots.
Solution
The given quadric equation is `x ^2 - kr + 4 = 0`, and roots are equal.
Then find the value of k.
Here, a = 1, b = -k and , c = 4
As we know that `D = b^2 - 4ac`
Putting the value of a =1,b = -k and , c = 4
=` (-k)^2 - 4 xx 1 xx 4`
=` k^2- 16`
The given equation will have equal roots, if D = 0
`k^2 - 16 = 0`
`k^2 = 16`
`k = sqrt 16`
=± 4
Therefore, the value of k =± 4 .
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