For which one of the following values of is the function defined for every real ?

MATHEMATICS · Single correct · A Level · Mathematics · Exponentials and logarithms · Exponentials and logarithms

Problem

For which one of the following values of

k

is the function

y=\log_{2}(x^{2}-kx+4)

defined for every real

x

? (a)

k=4

(b)

k=6

(c)

k=2

(d)

k=-4