Can anyone help with this?
Find all real numbers k, such that the roots of x^2 - 2kx + 5 = 0 are real. Enter your answer using interval notation.
If the roots are real.....then the discriminant is ≥ 0
So
(2k)^2 - 4(1)(5) ≥ 0
4k^2 - 20 ≥ 0
4k^2 ≥ 20
k^2 ≥ 5
Which implies that
k ≥ √5 or k ≤ - √5
(-inf , - √5] U [ √5, inf )