Question

if the sum of the zeros of a cubic polynomial , p(x) = 3x³-kx²+5x-7 is 2 , find the value of k​

Answer 1

Step-by-step explanation:

p(x) = 3x³-kx²+5x-7

p(2)=

${3 \times 2}^{3} - k \times 2 ^{2} + 5 \times 2 - 7$

$= 24 - 4k + 10 - 7$

= -4k + 24 + 3

= -4k + 27

now

-4k + 27 = 0

=> -4k = -27

=> k = 27/4

there fore

k is 27/4

Answer 2

We recall the concept of cubic polynomial

Cubic polynomial is that polynomial which has a degree $3$

Given:

        $p(x)=3x^{3}-kx^{2} +5x-7$

Let zeroes be $A,B,C$for the above polynomial

$A+B+C=-\frac{b}{a}$

               $2=\frac{k}{3}$......................[$b=-k$,$a=3$]

               $k=6$

The value of $k$ is $6$