Answer:
(x - 8)²
Explanation:
x² - 16x + 64
consider the factors of the constant term (+ 64) which sum to give the coefficient of the x- term (- 16)
the factors are - 8 and - 8 , since
- 8 × - 8 = + 64 and - 8 - 8 = - 16 , then
x² - 16x + 64
= (x - 8)(x - 8)
= (x - 8)²