If one root of x3+3x2+5x+k=0  is sum of the other two roots, then k =

The given equation is f(x)=x3+3x2+5x+k=0  By the given condition, one root is sum of other two roots⇒α=β+γ ∴  sum of the roots : α+β+γ=−3 ⇒2α=−3⇒α=−32 ∴f(−32)=(−32)3+3(−32)2+5(−32)+k=0 After simplification we get, k=338