1. penyelesaian persamaan 4 cos^2 x + ( 2-2 √2) cos x– √2=0 adalah 2. Nilai tan x yg memenuhi persamaan 2 cos^2 x + 3 cos x – 2 =0 adalah

1) 4 cos²x + (2 - 2√2)cos x - √2 = 0
4.cos²x + 2.cos x - 2√2cos x - √2 = 0
2.cos x(2.cos x + 1) - √2(2.cos x + 1) = 0
(2.cos x - √2)(2.cos x + 1) = 0
2.cos x - √2 = 0
2.cos x = √2
cos x = √2/2
cos x = cos 30°
x = 30°
2.cos x + 1 = 0
2.cos x = -1
cos x = -½
cos x = cos 120°
x = 120°

2) 2.cos²x + 3.cos x - 2 = 0
(2.cos x - 1)(cos x + 2) = 0
cos x + 2 = 0
cos x = -2 (tidak memenuhi)
2.cos x - 1 = 0
2.cos x = 1
cos x = ½
cos x = cos 60°
x = 60°
tan x = tan 60° = √3