Answer:
D. 225/4
Step-by-step explanation:
To complete the square (a technique that can be applied to many problems!), take half the coefficient of x and square the result.
The coefficient of x is 15. Half of 15 is 15/2. Square 15/2 to get 225/4.
Check:
[tex]x^2+15x+\frac{225}{4}=\left(x+\frac{15}{2}\right)\left(x+\frac{15}{2}\right)=\left(x+\frac{15}{2}\right)^2[/tex]
