Question

Prove that x^2+kx+2=0 has real roots if k>=2underroot2

Answer 1

Answer:

Given x

2

+kx+k

roots are real & equal

∴b

2

−4ac=0

=(k)

2

−4(1)(k)=0

=k

2

−4k=0

=k(k−4)=0

∴ k = 0 or k = 4

Answer 2

Answer:

for having real roots discriminate should be greater than zero . so

ksquare -4(2)> 0

so k >= 2√2