Д=64-4*15=4
х1=-8+2÷2=3
х2=8+2÷2=5
д=16+4×21=100
х1=-4+10÷2=3
х2=4+10÷2=7
<span>1)Sin 3x - Cos 3x = 2
По формуле: </span>Sin x - Cos x =
(sin(x - π/4)) = 0
(sin(3x - π/4)) = 2
sin(3x - π/4) =
3x - π/4 = (-1)^n × arcsin
+ πn (n ∈ Z)
3x = (-1)^n × arcsin
+ π/4 + πn (n ∈ Z)
x =
× (-1)^n × arcsin
+ π/12 + πn/3 (n ∈ Z)
Ответ: x =
× (-1)^n × arcsin
+ π/12 + πn/3 (n ∈ Z)
Cos2α/sin2α·(1-cos4α)=
1-cos4α=1-1+2sin²2α=2sin²2α
=2sin²2α*cos2α/sin2α=2sin2α*cos2α=sin4α
{x-5≠0⇒x≠5
{35x-6x²-11≥0
6x²-35x+11≤0
D=1225-264=961
x1=(35-31)/12=1/3
x2=(35+31)/12=5,5
1/3≤x≤5,5
x∈[1/3;5) U (5;5,5]