Question

5. If one zero of the quadratic
polynomial 2x²+kx-15 is 3, then
the other zero is​

Answer 1

Answer:

-5/2

Step-by-step explanation:

let two roots be p and q.

p=3,we need to find q

sum of roots= p+q =-(b/a).

3+q=(-k/2).............(1)

product of roots=p.q=c/a

3.q=-15/2

q=-5/2

from (1)

1/2=-k/2

k=-1

q is other root =-5/2

Answer 2

Solution:

f(x) = 2x^2 + kx - 15

d(x) = x - 3 , x = 3

f(x) = 2x^2 + kx - 15

f(3) = 2(3)^2 + k(3) - 15

= 18 + 3k - 15

= 3k + 3

-3k = 3

k = -1

Therefore, 2x^2 + kx - 15 = 2x^2 - x - 15

Factor out 2x^2 - x - 15 = (x - 3) (2x + 5)

(x - 3) (2x + 5) = 0

x = 3 and x = -5/2

Hope this will be helpful.