Answer:
The correct option is C.
Step-by-step explanation:
The given function is
[tex]f(x)=x^2-81[/tex]
Equate the given function equal to zero, to find the x-intercepts of the function.
[tex]f(x)=0[/tex]
[tex]x^2-81=0[/tex]
Add 81 both the sides.
[tex]x^2=81[/tex]
Taking square root both the sides.
[tex]x=\pm \sqrt{81}[/tex]
[tex]x=\pm 9[/tex]
The x-intercepts of the given function are -9 and 9. Therefore the correct option is C.
