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

1 Answer
Dec 11, 2017

#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#.