9lg^2(x)+15lgx-6=0
lgx=t
3t^2+5t-2=0
(-5+-sqrt(25+24))/6
t1=-2
t2=1/3
x=10^(1/3)
x=10^(-2)=0,01
-2sqrt(2)cos^3(3x)+2cos^2(3x)=0
cos3x=0
3x=П/2(2k+1)
x=П/6(2k+1)
cos3x=1/sqrt(2)
3x=+-П/4+2Пk
x=+-П/12+2/3Пk
