Question

If one zero of the quadratic polynomial 4x^2+(2k+1)x-9 is negative of the other, find the value of k

Answer 1

p(x) = 4x² + (2k + 1)x - 9

On comparing this with the standard form of quadratic polynomial ( i.e., ax² + bx + c ) , we get

a = 4 , b = (2k + 1) , c = -9

Given that one of the two zeroes is negative of the other, Now

☛ sum of zeroes in a quadratic polynomial = - b/a

{ Let one of the two zeroes be x then the other one will be -x }

☛ x + (-x) = - (2k + 1)/4

☛ 0 = -2k - 1/4

☛ -2k = 1

☛ k = -1/2

Hence, the value of k is -1/2