1
сtg3x-ctgx=0
sin(3x-x)/sin3x*sinx=0
sin2x=0 U sin3x*sinx≠0
2x=πn⇒x=πn/2,n∈z U x≠πk,k∈z U x≠πm/3,m∈z
x=πn/2,n∈z U n≠2m/3,m∈z
3
sin(2x+4x)/cos2xcos4x=sin(5x+x)/cos5xcosx
sin6x/cos2xcos4x-sin6x/cos5xcosx=0
sin6x(cos5xcosx-cos2xcos4x)/cosxcos2xcos4xcos5x=0
cosxcos2xcos4xcos5x≠0
sin6x=0⇒x=πn/6,n∈z
cos5xcosx-cos2xcos4x=0
1/2*cos4x+1/2*cos6x-1/2*cos2x-1/2*cos6x=0
1/2*cos4x-1/2*cos2x=0
-1/2*2sinxsin3x=0
sinx=0⇒x=πk,k∈z
sin3x=0⇒x=πm/3,m∈z
-х^2 -2х-1=0
х^2+2х+1=0
(х+1)^2=0
х= -1
Ответ: -1
Решение в приложении ↓ ↓ ↓
log2(7)*log7(4)=log7(2^2)/log7(2)=2log7(2)/log7(2)=2
Ответ: 2