+0  
 
0
38
1
avatar

Solve 9^(3 - x) = 81^(4 - 2x).

 Jan 6, 2020
 #1
avatar+19815 
+2

9^(3-x) = 9^2(4-2x)

equate the exponents

3-x = 8-4x

3x = 5

x = 5/3

 

Another way:

 

If you take the LOG of both sides you will get this:

(3-x) Log 9   = (4-2x) log 81

(3-x)/(4-2x) = log81/log9

(3-x)/(4-2x) = 2

3-x = 8-4x

-5 = -3x

x = 5/3

 Jan 6, 2020
edited by ElectricPavlov  Jan 6, 2020

9 Online Users