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

Answer 1

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