Factor 9y2 - 12y + 4.

(3 y - 2) (3 y + 2)

(3 y - 4) (y + 1)

(3 y - 2) 2

(y - 2) ²

Step-by-step explanation:

9y² - 12y + 4 ← is a perfect square of the form

(ax - b) ² = a²x² - 2abx + b²

Compare like terms with 9y² - 12y + 4, thus

a² = 9 ⇒ a = 3

b² = 4 ⇒ b = 2 and

- 2ab = - 2 * 3 * 2 = - 12

Thus

9y² - 12y + 4 = (3y - 2) ²