X² - kx+4-0
If the equation has
equal roots, then
b²-4ac=0
where a=1, b = -k and c=4

k = ± 4

Step-by-step explanation:

Given

x² - kx + 4 = 0 ← in standard form

with a = 1, b = - k, c = 4

The equation has equal roots, thus the discriminant

b² - 4ac = 0, that is

(- k)² - (4 × 1 × 4) = 0

k² - 16 = 0 ( add 16 to both sides )

k² = 16 ( take the square root of both sides )

k = ± = ± 4

d. all of the above

step-by-step explanation: