Question 343309
[2x^(3)-(4x^(2)-x-1)]-[9x^(3)-(x^(2)+5x-3)]

Multiply -1 by each term inside the parentheses.
2x^(3)-4x^(2)+x+1-[9x^(3)-(x^(2)+5x-3)]

Multiply -1 by each term inside the parentheses.
2x^(3)-4x^(2)+x+1-(9x^(3)-x^(2)-5x+3)

Multiply -1 by each term inside the parentheses.
2x^(3)-4x^(2)+x+1-9x^(3)+x^(2)+5x-3

Since 2x^(3) and -9x^(3) are like terms, add -9x^(3) to 2x^(3) to get -7x^(3).
-7x^(3)-4x^(2)+x+1+x^(2)+5x-3

Since -4x^(2) and x^(2) are like terms, subtract x^(2) from -4x^(2) to get -3x^(2).
-7x^(3)-3x^(2)+x+1+5x-3

Since x and 5x are like terms, add 5x to x to get 6x.
-7x^(3)-3x^(2)+6x+1-3

Subtract 3 from 1 to get -2.
-7x^(3)-3x^(2)+6x-2