1)5-5сos²x+4cosx-4=05cos²x-4cosx-1=0cosx=a5a²-4a-1=0D=16+20=36a1=(4-6)/10=-0,2⇒cosx=-0,2⇒x=π+_arccos0,2+2πna2=(4+6)/10=1⇒cosx=1⇒x=2πn2)6-6sin²x-5sinx-7=06sin²x+5sinx+1=0sinx=a6a²+5a+1=0D=25-24=1a1=(-5-1)/12=-1/2⇒sinx=-1/2⇒x=(-1)^n+1*π/6+πna2=(-5+1)/12=-1/3⇒sinx=-1/3⇒x=(-1)^n+1*arcsin1/3+πn3)2-2sin²x/3+3sinx/3=02sin²x/3-3sinx/3-2=0sinx/3=a2a²-3a-2=0D=9+16=25a1=(3-5)/4=-1/2⇒sinx/3=-1/2⇒x/3=(-1)^n+1*π/6+πn⇒x=(-1)^n+1*π/2+3πn2-2cos²3x-5cos3x-4=02cos²3x+5cos3x+2=0cos3x=a2a²+5a+2=0D=25-16=9a1=(-5-3)/4=-2⇒cos3x=-2 нет решенияa2=(-5+3)/4=-1/2⇒cos3x=-1/2⇒3x=+-2π/3+2πn⇒x=+-2π/9+2πn/3