Answer:
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 = ± [tex]\sqrt{16}[/tex] = ± 4
