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
Ответ:
..................................
Решение:
4.8х+14.8-2.8=5,2х
4.8х+5.2х=14.8-2.8
10х=12
х=12:10
х=1.2
![\frac{(n+1)!}{n!} = \frac{(n+1)*n!}{n!} =n+1 ](https://tex.z-dn.net/?f=+%5Cfrac%7B%28n%2B1%29%21%7D%7Bn%21%7D+%3D+%5Cfrac%7B%28n%2B1%29%2An%21%7D%7Bn%21%7D+%3Dn%2B1%0A%0A%0A%0A%0A%0A%0A+)
-------------------------------------------------------------------------
![\frac{(n+1)!(n+3)}{(n+4)!}=\frac{1}{(n+2)(n+4)}](https://tex.z-dn.net/?f=++%5Cfrac%7B%28n%2B1%29%21%28n%2B3%29%7D%7B%28n%2B4%29%21%7D%3D%5Cfrac%7B1%7D%7B%28n%2B2%29%28n%2B4%29%7D+)