Answer:
x^3+9x^2-3x^2-3
Explanation:
You can use a various of methods but when you use the box method you multiply each separately.
Like you would multiply x² by x, 8x by x, -3 by x (thats the first row)
x² by 1, 8x by 1, -3 by 1 ( for the second row)
Then you get those final variables and combine like terms getting the answer above