У-1,08=1+0,2у
у-0,2у=1+1,08
0,8у=2,08
у=2,08:0,8
у=2,6
ответ: 2,6
1)sinx=1/2; x∈[-2π;2π]
x=(-1)ⁿπ/6+πn
x=-11π/6;-7π/6;π/6;5π/6∈[-2π;2π]
2)sinx=√2/2; x∈[-π;2π]
x=(-1)ⁿπ/4+πn
x=π/4;3π/4∈[-π;2π]
3)sinx=√2/2; x∈[-2π;π/2]
x=(-1)ⁿπ/4+πn
x=-7π/4;-5π/4;π/4∈[-2π;π/2]
Х = + - arccos(0,3) + 2 pi*k; k-Z