X^3+4x^2+16x+3x^2+12x+48=x^3+7x^2+28x+48.
6х-6*3-6*х/6=6+*1
6х-18-х=6
5х-18=6
5х=6+18
5х=24
х=24/5=4 целых 4/5
<span>8< х <11 => 24< 3x < 33
</span> => 17 < 3x-1/2y<31
<span>8< у<14 => -7 < -1/2y < -4 </span>
Ctg²a(1 - Cos2a)² + Cos²2a = Cos²a/Sin²a(Sin²a + Cos²a - Cos²a + Sin²a)² +
+ Cos²2a = Cos²a/Sin²a(2Sin²a)² + Cos²2a = Cos²a/Sin²a * 4Sin^4a + Cos²2a =
= 4Sin²aCos²a + ( 2Cos²a - 1)² = 4Sin²aCos²a + 4Cos^4a - 4Cos²a + 1 =
= (4Sin²aCos²a + 4Cos^4a) - 4Cos²a + 1 = 4Cos²a(Sin²a+ Cos²a) - 4Cos²a + 1 =4 Cos²a - 4Cos²a + 1 = 1