5x-2=9x+4 /+2
5x=9x+6 /-9x
-4x=6
x=-6/4.x=-3/2
x=-1,5
6x=-8
x=-8:6
1
X1=-1-
3
1
x2=1-
3
Log81(6^4)*log6(9) = log9^2 (6^4) * log6(9) = 4/2 log9(6) * log6(9) = (дробь)(4*log9(6))/(9*log9(6)) = 4/2 = 2
Решение
sin2*18 / sin(2*18) = 1
sin2a=2sinacosa=-2*3*4/25=-24/25
sina=3/5 cosa=-4/5
tga/2=sina/(1-cosa)=sqrt(3)/2(1+1/2)=sqrt(3)/3
cosa=-1/2