SOLUTION
The expression is given as

The value of n makes the expression a perfect square trinomial.
To find the value of n, we have
Identify the coefficient of u and divide by 2

Then square the result, we have

Then the complete trinomial of the polynomial becomes

To factor as a square of a binomial we use the perfect square trinomial above

Therefore
The vaue of n = 100
The factor as the square of a binomial is (u+ 10)²