Question

If the sum of the zeroes of the quadratic polynomial 3x2-kx+6 is 3, then find the value of k.

Answer 1

Given :

Sum of the zeroes of the quadratic polynomial 3x² - kx + 6 is 3

To Find :

Value of k

Solution :

Given quadratic polynomial is

• 3x² - kx + 6

Compare given polynomial with

ax² + bx + c , we get ,

• a = 3  ,  b = - k  ,  c = 6

Sum of zeroes of the polynomial is given by ,

➠  $\sf -\dfrac{b}{a}$

where ,

• b denotes coefficient of x
• a denotes coefficient of x²

Given , Sum of zeroes = 3

➠  $\sf -\dfrac{b}{a}$ = 3

➠  $\sf -\dfrac{(-k)}{3}=3$

➠ - (-k) = 3 (3)

➠   k = 9  $\pink{\bigstar}$

So , Our required polynomial is

• 3x² - 9x + 6

Answer 2

Sum of the zeroes of the quadratic polynomial 3x² - kx + 6 is 3

To Find :

Value of k

Solution :

Given quadratic polynomial is

3x² - kx + 6

Compare given polynomial with

ax² + bx + c , we get ,

a = 3 , b = - k , c = 6

Sum of zeroes of the polynomial is given by ,

➠ \sf -\dfrac{b}{a}−

a

b

where ,

b denotes coefficient of x

a denotes coefficient of x²

Given , Sum of zeroes = 3

➠ \sf -\dfrac{b}{a}−

a

b

= 3

➠ \sf -\dfrac{(-k)}{3}=3−

3

(−k)

=3

➠ - (-k) = 3 (3)

➠ k = 9 \pink{\bigstar}★

So , Our required polynomial is

3x² - 9x + 6