What am I doing wrong?

Problem: 2x^2(5x^2-1x-4)

Answer: 10x^4-2x^3-8^2

The answer is correct.

Don't know what you did until you posted your work.

2 x ^ 2 ( 5 x ^ 2 - 1 x - 4 ) =

( 2 x ^ 2 * 5 x ^ 2 ) - ( 2 x ^ 2 * 1 x ) - ( 2 x ^ 2 * 4 ) =

10 x ^ 4 - 2 x ^ 3 - 8 x ^ 2

Based on the expression you provided, it seems like you have made a mistake in both the multiplication and the exponents. To correctly simplify the expression, you need to apply the distributive property and combine like terms.

Starting with the expression: 2x^2(5x^2 - x - 4)

To distribute 2x^2 to each term inside the parentheses:
2x^2 * 5x^2 = 10x^4
2x^2 * -x = -2x^3
2x^2 * -4 = -8x^2

Now, let's combine the like terms, which are the terms with the same exponent:
10x^4 - 2x^3 - 8x^2

So, the correct simplified form of the expression is 10x^4 - 2x^3 - 8x^2.