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Question
Choose the correct answer from the given four options :
The value(s) of k for which the quadratic equation 2x² – kx + k = 0 has equal roots is (are)
Options
0 only
4
8
0, 8
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Solution
2x² – kx + k = 0
a = 2, b = -k, c = k
∴ b2 - 4ac
= (-k)2 - 4 x 2 x 4
= k2 - 8k
∴ Roots are equal.
∴ b2 - 4ac = 0
k2 - 8k = 0
⇒ k(k - 8) = 0
Either k = 0
or
k - 8 = 0,
then k = 8
k = 0, 8.
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