Question

3 raise to the power x-1 + 3 raise to the power x+1 = 90 then x is equal to ?

Answer 1

Answer:

You can solve this in 3 ways

1. Substitute 3^x = a (or any variable you want), then, rewrite the equation and solve further to get a = 27 = 3^x

therefore x=3

2. Take 3^(x-1) common to get the equation

3^(x-1){1+(3^2)} = 90, which on solving gives you 3^(x-1) = 9, Thus x= 3

3. Write 90 as a sum which suits the format of equation as

90 = 9 + 81 (you can do this by writing down the values of 3^x)

by this you can figure out value of x