27. 1) (2,6x-4)= -30 +5,09x; 3) 3(17 - 22.1.) - - - вопрос №2016078427126430509331722176342201 от Bossip 17.04.2023 03:36

Question

Алгебра: 27. 1) (2,6x-4)= -30 +5,09x; 3) 3(17 - 22.1.) - - 7 - 63,4 x; 2) 20,1 x - 1,1 = 4(10 – 5,25x); 4) 19x -0,4 = 2(32 x – 5) +0,6. даю 15 б

Bossip · Answer

1 1
-- (cos6x + 4cos3x + 3) - -- (cos6x - 4cos3x + 3) =
8 8

1    1
= ( cos6x + 4cos3x + 3 - cos6x + 4cos3x - 3) = --- 8cos3x = cos3x
8    8

а сорь, там равно 1/2
Тогда, cos3x = 1/2
3x = +arccos1/2 + 2pk
3x = - arccos1/2 + 2pk

3x = pi/3 + 2pk
x1 = pi/9 + 2pk/3

x2 = -pi/9 + 2pk/3