(558²-23²):581=(558-23)(558+23):581=535·581:581=310835:581=535.
Sin² x - 6 cos² x - 5sinx*cosx=0
ДЕЛИМ НА COS²X
tg²x-5tgx-6=0
D=25+24=49; √D=7
tgx=(5+7)/2=6; tgx=-1
x=arctg6+πn.... x=-π/4+πn
ОДЗ
x > 0,5
lg(4x - 2) = lg(2^4)
lg(4x - 2) = lg(16)
4x - 2 = 16
4x = 18
x = 4,5
Ответ
4,5