Question

If the sum of two roots of the equation $x^3-3x^2-16x+k=0$ is zero, then $k$ is equal to

• A. $24$
• B. $36$
• C. $-36$
• D. $48$

Answer 1

Answer: (D)

$48$

Sum of the roots is $3$ as per the coefficients and roots relation

Since sum of two of the roots is zero,we get the other root as $3$

Now put the value $x=3$ in equation and equate to $0$

$\Rightarrow 3^3-{3.3}^2-16.3+k=0$

$k-48=0$

$\therefore k=48$