Question

How do you solve `f( x ) = 2^ { ( 22- x ) } - 21`?

Answer 1

`x=22-log_2(21)\approx17.61`

Explanation:

I will be assuming that the question is asking for the zeros of the function `f(x)=2^(22-x)-21`.

First, set it equal to zero:
`2^(22-x)-21=0`

Then, bring the `-21` over to the right-hand side:
`2^(22-x)=21`

Find the `log_2` of both sides:
`22-x=log_2(21)`

Add `x-log_2(21)` to both sides:
`22-log_2(21)=x`

Using a calculator, we find that `x\approx17.61`.