4,72-2,5х=2х+2,92
-2,5х-2х=2,92-4,72
-4,5х= -1,8
х=0,4
.............................
5/8=0,625 3/4=0,75 2 2/5=2,4
0,625у-0,75=2у-2,4
0,625у-2у= -2,4+0,75
- 1,375у= - 1,65
у=1,2
1/(1-tga)-1/(1+tga)-tg2a=1/(1-tga)-1/(1+tga)-2tga/(1-tg²a)=
=(1+tga-1+tga-2tga)/(1-tg²a)=0/(1-tg²a)=0
cos36cos72-1/4=2sin36cos36cos72/2sin36 -1/4=sin72cos72/2sin36 -1/4=
=sin144/4sin36 -1/4=sin(180-36)/4sin36 -1/4=sin36/4sin36 -1/4=1/4-1/4=0
62472/12=5206
16742*17=284614
5206+284614=289820
289820-289325=495
Ответ: 495