The answer is correct.
Don't know what you did until you posted your work.
What am I doing wrong?
Problem: 2x^2(5x^2-1x-4)
Answer: 10x^4-2x^3-8^2
2 answers
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
( 2 x ^ 2 * 5 x ^ 2 ) - ( 2 x ^ 2 * 1 x ) - ( 2 x ^ 2 * 4 ) =
10 x ^ 4 - 2 x ^ 3 - 8 x ^ 2