Answer:
-6x^3 + x^2 - 20
Explanation:
First step: write down the problem.
2nd step:
Just lose the first set of parentheses. Write the first four terms exactly the same. Remove also the second set of parentheses but distribute that minus sign to all the last four terms. You get:
-6x^2+4x^3-9x-10-10x^3+7x^2+9x-10
Then combine like terms. Terms with the same exponent can be added or subtracted.
Standard Form means the highest exponent is written first, then the next lower exponent, and then the next lower exponent with a constant (number only) at the end.
So we do the third power first. Then 2nd power. (The x's drop out because -9x and +9x) and constants last.
-6x^3 + x^2 - 20