Question

if one of the zeros of the quadratic polynomial (k-2)x^2 -2x-k(k+5) is 4 ,find k

Answer 1

Answer:

ANSWER

Given : One of the zeros of quadratic polynomial (k−1)x

2

+kx+1 is −3

To find : Value of k

Solution : As −3 is one of the zeros of quadratic polynomial (k−1)x

2

+kx+1

⇒ When we substitute −3 in the polynomial , we get 0

⟹(k−1)(−3)

2

+k(−3)+1=0

⟹9k−9−3k+1=0

⟹6k−8=0

or k=

6

8

=

3

4

Answer 2

Given : One of the zeros of quadratic polynomial

(k-2)x^2 -2x-k(k+5) is 4

To find : Value of k

Solution : As 4 is one of the zeros of quadratic polynomial (k-2)x^2 -2x-k(k+5)

=> When we substitute 5 in the polynomial , we get 0

=> (k-2)x^2 -2x-k(k+5) = 0

=> (k-2) (4)^2 - (2×4 )-k(k+5) =0

=>( k-2)16 -8-k^2-5k = 0

=> 16k - 32 - 8 - k^2 - 5k =0

=> 3k - 40 -k^2 = 0

Rearranging we get ,

=> -k^2 + 3k - 40= 0

=> -k^2 + 8k - 5k -40 = 0

=> -k ( k + 8) -5 ( k + 8 ) = 0

=> (k+8)(-k-5) =0

thus , k +8 = 0

thus , k +8 = 0therefore, k = -8 ,OR

-k-5 =0

thus, k = 5