2y²(6y-1)+3y(y-4y²)

To simplify the expression, we can start by distributing the terms:

2y²(6y-1) + 3y(y-4y²)

First, let's distribute the 2y² to each term inside the parentheses:

12y³ - 2y² + 3y(y-4y²)

Next, distribute the 3y to each term inside the parentheses:

12y³ - 2y² + 3y² - 12y³

Now, combine like terms:

(12y³ - 12y³) + 3y² - 2y²

Simplifying further, we get:

0 + y²

Therefore, the simplified expression is:

y²