Question

Find the value of ‘k’ for which the quadratic equation 2kx² – 40x + 25 = 0 has real and equal roots.

Answer 1

Given quadratic equation is 2kx² – 40x + 25 = 0

On comparing the above equation with ax² + bx + c = 0, we get

a = 2k, b = –40, c = 25

For real and equal roots, D = 0

i.e., b² – 4ac = 0

or, (–40)² – 4(2k)(25) = 0

⇒ 1600 – 200k = 0

⇒ 200k = 1600

⇒ k = 8