3х² -2х -3=0
D = 2² -4*3(-3) = 4+36=40
√D =√40 = 2√10
x₁ = (2-2√10)6 = (1-√10)/3
x₂ = (2+2√10)/6 = (1+√10)/3
Ответ: (1-√10)/3; (1+√10)/3
11х-4х>8.8+5.2
7х>14
х>2
18.9x-13.4<10.1x+13
18.9x-10.1x<13.4+13
8.8x<26.4
x<3
Cos^2x = 1/2
cosx = - √2/2
x₁ = ± arccos(-√2/2) + 2πn
x₁ = ± (π - π/4) + 2πn
x₁= ± 3π/4 + 2πn, n∈Z
cosx = √2/2
x₂ = ± arccos(√2/2) + 2πk
x₂ = ± π/4 + 2πk, n∈Z
Построила в Екселе с таблицей, взяла х(-10;10) с щагом 1.