Final answer:
To complete the square for the quadratic expression n^2 - 28n, add 196 to the expression, which becomes n^2 - 28n + 196. This factors to (n - 14)^2.
Step-by-step explanation:
To complete the square for the quadratic expression n2 - 28n, you need to find a constant that will turn the expression into a perfect square trinomial.
The process involves taking half of the linear coefficient (which is -28 in this case), squaring it, and adding it to the expression. So, you take -28, divide it by 2 to get -14, and then square -14 to get 196. Therefore, the number you need to complete the square is 196, making the expression n2 - 28n + 196, which factors to (n - 14)2.