Question:
[tex]f(x)=9 , f(x)=-3x-3[/tex]
Solution:
When [tex]f(x)[/tex] is equal to 9 that means [tex]f(x)=-3x-3[/tex] is equal to 9 too which you can solve by:
[tex]9=-3x-3\\ 9+3=-3x-3+3\\ 12=-3x\\\frac{12}{-3}=\frac{-3x}{-3}\\-4=x[/tex]
Answer:
[tex]x=-4[/tex]
Check:
[tex]-3(-4)-3\\-12-3\\=9[/tex]
Hope this was helpful.