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Question
Choose the correct answer for the following question.
The roots of x2 + kx + k = 0 are real and equal, find k.
Options
0
4
0 or 4
2
Solution
Given quadratic equation is x2 + kx + k = 0
For real and equal roots, D = 0
\[b^2 - 4ac = 0\]
\[ \Rightarrow k^2 - 4 \times 1 \times k = 0\]
\[ \Rightarrow k^2 - 4k = 0\]
\[ \Rightarrow k\left( k - 4 \right) = 0\]
\[ \Rightarrow k = 0, k = 4\]
Hence, the correct answer is 0 or 4.
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