Find the value of k for which the quadratic equation 2x2+8x-k3=0 has two equal roots

Question

If the quadratic equation 2x²+8x-k³=0 has two equal roots then find the value of k

Answer 1

Given equation, 2x²+8x-k³=0

Here, a = 2, b = 8, c = -k³

Since roots are equal

So, b² - 4ac = 0

(8)² - 4 .2.(-k³)=0

64 + 8k³ = 0

8k³ = - 64

k³ = - 64/8

k³ = - 8

k³ = (-2)³

k= - 2

The value of k so that the equation 2x²+8x-k³=0 has two equal roots is -2.