Ireally need its a test

if f -1(x) is the inverse of f(x), which statements must be true?
check all that apply.
a. f ^-1(f(x)) = x
b. f(f ^-1(x)) = x
c. the domain of f ^-1(x) is the domain of f(x).
d. the domain of f^ -1(x) is the range of f(x).
e. the range of f^ -1(x) is the domain of f(x).
f. the range of f^-1(x) is the range of f(x).

Aculture started with 3000 bacteria. after 5 hours it grew to 3900 bacteria. predict how many bacteria will be present after 9 hours

Zroms according to the synthetic division below, which of the following statements are true? check all that apply. 352 -2 6 -12 12 2 4 0 i a. (x-3) is a factor of 2x2 - 2x - 12. b. the number 3 is a root of f(x) = 2x2 - 2x - 12. c. (2x2 - 2x - 12) = (x + 3) = (2x + 4) d. (2x2 - 2x-12) - (x-3) = (2x + 4) e. (x+3) is a factor of 2x2 - 2x - 12. o f. the number -3 is a root of fx) = 2x2 - 2x - 12. previous

Suppose y varies directly with x. write a direct variation equation that relates x and y. then find the value of y when x=12 y=7 when x=3