Question

How do you solve `2^(x) + 2^(2x) = 72`?

Answer 1

`x = 3`

Explanation:

Taking `y = 2^x` we have

`y+y^2=72`

Solving for `y` we get

`{y = -9},{y = 8}`

but `y = 2^x` must be positive then we follow with

`y = 2^x = 8->x = 3`