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Question
For the equation given below, find the value of ‘m’ so that the equation has equal roots. Also find the solution of the equation:
3x2 + 12x + (m + 7) = 0
Solution
3x2 + 12x + (m + 7) = 0
Here a = 3, b = 12 and c = m + 7
Given equation has equal roots
Then D = 0
`=>` b2 – 4ac = 0
`=>` (12)2 – 4(3)(m + 7) = 0
`=>` 144 – 12m – 84 = 0
`=>` – 12m = – 60
`=>` m = 5
Put value of m in given equation
3x2 – 12x + 12 = 0
`=>` x2 + 4x + 4 = 0
`=>` (x + 2)2 = 0
`=>` x + 2 = 0
`=>` x = – 2
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