Question

Which function is the inverse of ?
f(x)=50,000(0.8)^x

Answer 1

Answer:

y=log(x)−log(50000)log(0.8)

Explanation:

write as : y=50000(0.8)x

Taking logs:

log(y)=log(50000)+log(.(0.8)x.)

But log(.(0.8)x.) is the same as xlog(0.8)

Thus
x=log(y)−log(50000)log(0.8)

Now swap the x'x and the y's giving:

y=log(x)−log(50000)log(0.8)

my teacher helped a little bit