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Question
If the quadratic equation x2 + 4x + k = 0 has real and equal roots, then ______.
Options
k < 4
k > 4
k = 4
k ≥ 4
Solution
If the quadratic equation x2 + 4x + k = 0 has real and equal roots, then k = 4.
Explanation:
x2 + 4x + k = 0
Discriminant = 0
b2 – 4ac = 0
16 – 4(1)(k) = 0
16 – 4k = 0
`\cancel–` 4k = `\cancel–` 16
k = `16/4`
k = 4
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