Answer:
The answer is D: x (Squared) + 4x - 21.
Explanation:
(X-3)(x+7)
First you multiply the first x by x, to get x squared. Then you multiply the first x by 7 to get 7x.
Next you multiply the -3 by the second x, to get -3x. Then you multiply the -3 by the 7 to get -21.
Written in order it would look like:
X (squared) + 7x -3x -21
You can combine the 7x and the -3x because they are like terms. This would leave you with:
x (squared) + 4x - 21