5. Given the function f(x) = log4(x + 8), find the value of f^−1(2).

A. f−1(2) = 4

B. f−1(2) = 8

C. f−1(2) = 10

D.f−1(2) = 17

Question

5. Given the function f(x) = log4(x + 8), find the value of f^−1(2).

A. f−1(2) = 4

B. f−1(2) = 8

C. f−1(2) = 10

D.f−1(2) = 17

anonymous · Answer

c

anonymous · Answer

how did you get the answer @gabriel54321 ?? I don't just want to cheat I wan't to learn.. @phi

phi · Answer

$$ f^{-1}(2) $$  means find the value of f_inverse when it is given 2 as its input.

they don't give you f_inverse, they give you f(x).

anonymous · Answer

so $$f^-1 (2) = \log_{4}(x+8 $$

phi · Answer

I just memorize that $ f^{-1}(2)$ means  we can replace f(x) with 2 and solve for x
using
$$  f(x) = \log_4(x + 8) \ 2 = \log_4(x + 8)$$

anonymous · Answer

so it would equal 8

phi · Answer

we use the idea that the "input" to f_inverse is the same as the output of f()
$$ f^{-1}(a) = b  \leftrightarrow  f(b)= a $$

anonymous · Answer

f^-1 (2) = 8

phi · Answer

to solve we do this
$$ 2 = \log_4(x+8) $$
make each side the exponent to the base 4
$$ 4^2 = 4^{\log_4(x+8)} \16= x+8 \ 8=x $$

anonymous · Answer

thank you