(12)2t-9=164
24t-9=164
24t=164+9
24t=173
t=173:24
t=7 5/24
X² + px + q = 0
x₁ = - 7
x₂ = - 2
По т.Виета имеем:
x₁ + x₂ = - p
x₁ * x₂ = q
-7 + (- 2) = - 9, p = 9
x₁ * x₂ = (-7)*(-2) = 14, q = 14
Получаем квадратное уравнение:
x² + 9x + 14 = 0
cos x=t,
6t²-7t-5=0,
D=169,
t1=-½, t2=1 ⅔>1,
cos x=-½,
x=±arccos (-½) + 2πk, k∈Z,
x=±(π-arccos (½)) + 2πk, k∈Z,
x=±(π-π/3) + 2πk, k∈Z,
x=±2π/3 + 2πk, k∈Z,
-7π/2<±2π/3 + 2πk<-5π/2,
[-7π/2-2π/3<2πk<-5π/2-2π/3, -7π/2+2π/3<2πk<-5π/2+2π/3,
[-25π/6<2πk<-19π/6, -17π/6<2πk<-11π/6,
[-25/12<k<-19/12, -17/12<k<-11/12,
[k=-2, k=-1,
x=2π/3 - 4π,
x=-10π/3;
x=-2π/3-2π,
x=-8π/3.
Если я правильно поняла...
0,01 = 1\%, 0,1 = 10\%, 1 = 100\% , значит
24\%
30\%
38\%
50\%
76\%
90\%