Answer:
see explanation
Step-by-step explanation:
Using the method of completing the square
Given
x² - 8x + 20
add/subtract ( half the coefficient of the x- term)² to x² - 8x
= x² + 2(- 4)x + 16 - 16 + 20
= (x - 4)² + 4 ← with a = 4
(b)
For all real values of x, (x - 4)² > 0, hence (x - 4)² + 4 > 0 and therefore
x² - 8x + 20 is always positive
