The solution of 3tan2x - 1 = 0 if x is in the first quadrant is

The equation is

3 tan2x - 1 = 0

The condition is that x is in the first quadrant or it has a positive angle and is less than 90 degrees.

Solving the equation

3 tan2x = 1

tan2x = 1/3

2x = tan⁻¹ (1/3)

x = tan⁻¹ (1/3) / 2

x = 9.22 degrees