kak ada yang tau jalan no 25 gak ya

tan 2x = 2tan x / 1 - tan^2 x
2tan x / 1 - tan^2 x = 3
3( 1 - tan^2 x ) = 2tan x
3 -3tan^2 x = 2tan x
3tan^2 x +2tan x -3 = 0
misal tan x = a, maka
3a^2 +2a -3 = 0
a1,2 = {-2 +/- √(2^2-4.3.-3) }/ 2.3
a1.2 = { -2 +/- √40)/6
a1.2 = (-2 +/-2√10)/6
a1 = -1/3+1/3√10 = 1/3(√10-1)....(C)
a2 = -1/3-1/3√10 = -1/3(√10+1)