(201²-99²)×3^3n-5/3^3n-3=( 201-99)(201+99)×3^(3n-5-3n+3)=
=102×300×3-²=34×100=3400
Cos(3x+π/6)=-√3/2
3x+π/6=-5π/6+2πk U 3x+π/6=5π/6+2πk
3x=-π+2πk U 3x=2π/3+2πk
x=-π/3+2πk/3 U x=2π/9+2πk/3,k∈z
X²=10-3x
x²+3x-10=0
p=3 q=-10
D= p²-4q= 9+40=49
x=-p+-√D деленные на 2 = -3+-7 деленные на 2
x1 = 4/2 = 2
x2 = -10/2 = -5