8,2*(75,38-46,18)=239,44
1)75,38-46,18=29,2
2)8,2*29,2=239,44
Cos2x + 10cosx - 11 = 0
cos^2 x - sin^2 x + 10 cosx - 11 = 0
cos^2 x - (1 - cos^2 x) <span>+ 10 cosx - 11 = 0
2cos^2 x </span><span>+ 10 cosx - 12 = 0, cos x = t
2t^2 + 10t - 12 = 0
t^2 + 5t - 6 = 0
D = 5^2 + 4*6 = 25 + 24 = 49
t1 = (-5 + 7)/2 = 2/2 = 1
t1 = (-5-7)/2 = -12/2 = -6 - лишний корень
cos x = 1
x = pin, n э Z </span>
Ответ:
Пошаговое объяснение:
-2/9+(2/9-3/4) = -2/9 + 2/9 - 3/4 = -3/4
4/7-(5/11-3/7) = 4/7 - 5/11 + 3/7 = 1 - 5/11 = 6/11
3 5/6+(-5/6-1/7) = 3 5/6 - 5/6 - 1/7 = 3 - 1/7 = 2 6/7
3/8-(1/9-5/8) = 3/8 - 1/9 + 5/8 = 1 - 1/9 = 8/9