Question

michele

If f(x) = log2 (x + 4), what is f^–1(3)?

Answer 1

@Michele_Laino 8 is answer?

Answer 2

Are you trying to find out what x =?

Answer 3

what is f^–1(3)

Answer 4

here we have:
\[\Large {f^{ - 1}}\left( x \right) = {2^x} - 4\]
so:
\[\Large {f^{ - 1}}\left( 3 \right) = {2^3} - 4 = ...?\]
more explanation:
we can write:
\[\Large f\left( {{f^{ - 1}}\left( x \right)} \right) = {\log _2}\left( {{2^x} - 4 + 4} \right) = {\log _2}\left( {{2^x}} \right) = x\]
here's why the inverse function is:
\[\Large {f^{ - 1}}\left( x \right) = {2^x} - 4\]

Answer 5

right michele? 8 is right?

Answer 6

\[{f^{ - 1}}\left( 3 \right) = {2^3} - 4 = 8 - 4 = ...?\]

Answer 7

4

Answer 8

that's right!

Answer 9

thank michele!

Answer 10

thanks! @sallyfield888