Answer:
C
Step-by-step explanation:
Given
x² - 6x + 9
Consider the factors of the constant term (+ 9) which sum to give the coefficient of the x- term (- 6)
The factors are - 3 and - 3, since
- 3 × - 3 = + 9 and - 3 - 3 = - 6, thus
x² - 6x + 9 = (x - 3)(x - 3) = (x - 3)² → C