Answer:
f(x)=x^2-6x-27
Explanation:
x=9 and x-3
set the equal to zero: x-9=0 and x+3=0
x-9 and x+3 are now the factors of your equation:
you equation so far is: (x-9)(x+3)=0
next factor these together to get: f(x)=x^2+3x-9x-27
finally simplify the equation leaving you with f(x)=x^2-6x-27