Question

If the sum of the zeroes of the cubic polynomial kx³-5x²-11x-3 is 5/3 then find the value of k

Answer 1

Sum of the zeros = a+b+c. [alpha+ beta+gamma]
= -b/a
= -(-5)/k=5/3
= 5/k = 5/3
= k= 3.

Answer 2

Given:

We have given a cubic polynomial kx³-5x²-11x-3 which has sum of zeroes is $\frac{5}{3}$.

To Find:

We have to find the value of k?

Step-by-step explanation:

• Cubic polynomial :
• A polynomial is said to be cubic when the highest degree of the polynomial is 3.
• Let us consider the general form of cubic polynomial which is written below

       $ax^3+bx^2+cx+d=0$

• Now we will compare the given equation with the equation written above we get

        a= k , b = -5 , c=-11 , d = -3

• Now sum of zeroes of cubic polynomial is given by the formula

       $\textrm{Sum of zeroes}=\frac{-b}{a}$

• Now we will put the values in the above equation

       $\frac{5}{3} =\frac{-(-5)}{k}$

• Now do the cross-multiplication and simplify them

      $5k=15\\k=3$

Hence, the value of k is 3.