Assuming that you want this simplified...
[tex]f(x) = (x + 3)^2 - 5[/tex]
[tex]--> = (x + 3)(x + 3) - 5[/tex]
Use the FOIL method and combine like terms:
[tex]f(x) = (x^2 + 3x + 3x + 9) - 5[/tex]
[tex]f(x) = x^2 + 6x + 9 - 5[/tex]
And your final answer is: [tex]f(x) = x^2 + 6x + 4[/tex]
