4/3x^2 (6x^2+9x-12)

To simplify the expression 4/3x^2 (6x^2+9x-12), we will use the distributive property of multiplication over addition.

Step 1: Distribute the 4/3x^2 to each term within the parentheses.
(4/3x^2 * 6x^2) + (4/3x^2 * 9x) + (4/3x^2 * -12)

Step 2: Simplify each term.
(24/3x^4) + (36/3x^3) + (-48/3x^2)

Step 3: Combine like terms.
24/3x^4 + 36/3x^3 - 48/3x^2

Step 4: Simplify the fractions.
8/x^4 + 12/x^3 - 16/x^2

Thus, the simplified expression is 8/x^4 + 12/x^3 - 16/x^2.