2y²(6y-1)+3y(y-4y²)

To simplify the expression 2y²(6y-1) + 3y(y-4y²), we will apply the distributive property and combine like terms.

First, we distribute 2y² to each term inside the parentheses: 2y²(6y-1) = 12y³ - 2y²

Next, we distribute 3y to each term inside the second set of parentheses: 3y(y-4y²) = 3y² - 12y³

Now, we can combine the like terms: 12y³ - 2y² + 3y² - 12y³

Combining 12y³ and -12y³, we get 0, which cancels out those terms: 0 - 2y² + 3y²

Combining -2y² and 3y², we get y²: y²

Therefore, the simplified expression is y².