Question

For what value of K, do the quadratic equation 9x^2-8kx+16=o have equal roots?

Answer 1

For an equation ax²+bx+c=0 to have equal roots, discriminant Δ =√(b²-4ac) = 0

i.e b²=4ac

Accordingly, here a=9,b=-8k,c=16

So, (-8k)²=4*9*16

⇒ k²= 4*9*16/64

⇒k=3 or -3