Question

The value of m for which the equation x^2+(m+3)x+m+6=0 has equal roots is

Answer 1

D = 0 for the given condition

D = b^2 - 4ac
= (m+3)^2 - 4(m+6)
= m^2 + 9 + 6m - 4m - 24
= m^2 + 2m - 15
= m^2 + 5m - 3m - 15 = 0
= m(m + 5 ) - 3(m + 5)
= (m - 3)(m + 5)
m = 3 and -5