Question

If one of the zero of the quadratic polynomial f(x) = 4x² – 8kx – 9 is negative of the other, then find the value of k.

Answer 1

From the question, it’s given that: 

The quadratic polynomial f(x) where a = 4, b = -8k and c = – 9 

And, for roots to be negative of each other, let the roots be α and – α. 

Sum of the roots = α – α = \(\frac{-b}{a}\) 

= – \(\frac{(-8k)}{1}\) 

= 8k = 0 [∵ α – α = 0] 

⇒ k = 0