To complete the square for the quadratic polynomial \( s^2 - 15s \), we need to find the value that makes it a perfect square.
- Start with the coefficient of \( s \), which is -15.
- Take half of this coefficient: \( \frac{-15}{2} = -\frac{15}{2} \).
- Square that result: \[ \left(-\frac{15}{2}\right)^2 = \frac{225}{4} \]
Now, we can fill in the blank:
The perfect square form of the polynomial \( s^2 - 15s + \frac{225}{4} \) is:
\[ \left(s - \frac{15}{2}\right)^2 \]
So, you need to add \( \frac{225}{4} \) to make \( s^2 - 15s \) a perfect-square quadratic.