Помогите решить cos^2x-sin(x+0,5pi)=2

Номер 473
1)
1,25×X=1
X=1:1,25=1/1 :125/100=1/1:5/4=1/1×4/5
X=4/5
2)
3 1/7×X=1
X=1:22/7=1/1×7/22
X= 7/22
3)
2 3/15×X=1
X=1:33/15=1/1×15/33
X=15/33
номер 474
1)
(1 5/8+19/24-1 1/12)×X=1
a)1 5/8+19/24=13/8+19/24=39/24+19/24=58/24=29/12=2 5/12
б) 2 5/12-1 1/12=29/12-13/12=16/12=4/3=1 1/3
в)
1 1/3×X=1
X=1:1 1/3= 1/1:4/3=1/1×3/4
X= 3/4
2)
(2 23/28+1 5/7-1 13/14)×X=1
a) 2 23/28+1 5/7=79/28+12/28=81/28=2 25/28
б) 2 25/28-1 13/14=81/28-27/14=81/28-54/28=27/28
в) 27/28×X=1
X= 1:27/28=1/1×28/27
X=28/27=1 1/27

1/3; 30;0,5/7;60;6см;0,008м; 2/300;50грамм;1/15грамм;39,1/130,1см

(x+3)/(x-3) +( х-3)/(х+3) - 10/3=0
(3(х+3)²+ 3(х-3)²- 10(х-3)(х+3))/ 3(х+3)(х-3) =0
(3х²+18х+27+3х²-18х+27-10х²+90)/ 3(х+3)(х-3)=0
(-4х²+144)/ 3(х-3)(х+3)=0
-4х²+144=0; х-3≠0; х+3 ≠0
-4х²=-144|:(-4); х≠3; х≠-3
х²=36
х=√36
х=±6

1 м3= 1000 дм3
1,35 м3= 1350 дм3
V= abc
c= V:ab
c= 1350 :(8*2,25)= 1350:18= 75 дм ширина

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