Answer:
(n - 3) (n + 7)
Explanation:
n² + 4n - 21
Consider the form x² + bx + c. Find a pair of integers whose product is
c and whose sum is b. In this case, whose product is −21 and whose sum is 4.
-3, 7
Write the factored form using these integers.
(n - 3) (n + 7)
So, the answer is (n - 3) (n + 7)