Домножим на 4
cos4x+2=4sin²x+2sin2x
cos4x+2=(1-cos2x)/2+2sin2x
cos4x+2=2-2cos2x+2sin2x
(cos2x-sin2x)(cos2x+sin2x)+2(cos2x-sin2x)=0
(cos2x-sin2x)(cos2x+sin2x+2)=0
cos2x-sin2x=0 /cos2x
1-tg2x=0
tg2x=1
2x=π/4+πk
x=π/8+πk/2,k∈z
cos2x+sin2x+2=0
cos²x-sin²x+2sinxcosx+2sin²x+2cos²x=0
sin²x+2sinxcosx+3cos2x=0/cos²x
tg²x+2tgx+3=0
tg2x=a
a²+2a+3=0
D=4-12=-8<0 нет решения
Ответ x=π/8+πk,k∈z
<span> (a-2)</span>³ = a³-6a²+12a-8.<span>
(3a+b)</span>³ = 27a³+27a²b+9ab²+b³.<span>
(c-4d)</span>³ = c³-12c²d+48cd²-64d³.<span>
(a+0,3bc)</span>³ = a³+0,9a²bc+0,27ab²c²+0,27b³c³.