Verified answer

If you meant:

fourth root(2x - 1) = 3

Raise everything to the 4th

(fourth root(2x - 1))^4 = 3^4

Power cancels with root

2x - 1 = 3^4

Simplify

2x - 1 = 81

Add 1

2x = 82

Divide by 2

x = 41

If you meant:

(fourth root(2x)) - 1 = 3

Add 3

fourth root (2x) = 4

Raise everything to the fourth power

(fourth root (2x))^4 = 4^4

The power and root cancel

2x = 4^4

Simplify

2x = 256

Divide by 2

x = 128

I hope this helps, have a good day.

Something wrong with you eq.