Answer:
[tex]f(x)=(x-4.5)^2-23.25[/tex]
Step-by-step explanation:
[tex]f(x)=x^2+9x-3\\\\f(x)+23.25=x^2+9x-3+23.25\\\\f(x)+23.25=x^2+9x-20.25\\\\f(x)+23.25=(x-4.5)^2\\\\f(x)=(x-4.5)^2-23.25[/tex]
Basically, you want the third term to be the square of half the middle term. Therefore, you need to add something to both sides to "complete the square" and reduce the trinomial into a square.
