Answer:
(5y² - 12y + 6) y²
Step-by-step explanation:
i'm going to assume that you mean to simplify the expression:
10y⁴+6y²-12y³-5y⁴ (group like terms)
= (10y⁴- 5y⁴) - 12y³ + 6y²
= 5y⁴ - 12y³ + 6y² (factor out y²)
= (5y² - 12y + 6) y²