Решите уравнение 2 ⅝x-1+2 5 x-2+2 5 x-3 =896
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1) 5х-3=0
5х=3
х=3:5
х= 0,6

2)4х-7=0
4х=7
х=7:4
х= 1,75

3)-4х+19=0
-4х=-19
х=19:4
х= 4,75

4)9х+10=10х
9х-10х=-10
-х=-10
х=10

5)5х-3=-10х
5х+10х=3
15х=3
х=3:15
х=0,2

6)2х+7=-2х
2х+2х=-7
4х=-7
х=-7:4
х=-1,75

7)-х-7=-5х
-х+5х=7
4х=7
х=7:4
х=1,75

8)2+8х=3х+9
8х-3х=9-2
5х=7
х=7:5
х=1,4

9)6-2х=3х-10
-2х-3х=-10-6
-5х=-16
х=16:5
х=3,2

10)5-2х=8х+9
-2х-8х=9-5
6х=4
х=4:6
х=0,6

11)2(х-7)=3
2х-14=3
2х=3+14
2х=17
х=17:2
х=8,5

12)5(х+9)=-2
5х+45=-2
5х=-2-45
5х=-47
х=47:5
х=9,4

13)3=4(х+2)
3=4х+8
-4х=8-3
-4х=5
-х=5:4
х=-1,25

14) 7(-3+2х)=-6х-1
-21+14х=-6х-1
14х+6х=-1+21
20х=20
х=1

15)2(7+9х)=-6х+2
14+18х=-6х+2
18х+6х=2-14
24х=-12
х=-12:24
х=-0,5

16)6(5-3х)=-8х-7
30-18х=-8х-7
-18х+8х=-7-30
-10х=-37
х=37:10
х=3,7

17)7(-5+3х)+4х=9
-35+21х+4х=9
21х+4х=9+35
25х=44
х=44:25
х=1,76

18)3(-1-х)-2х=9
-3-3х-2х=9
-3х-2х=9+3
-5х=12
х=-2,4

19)6(4-х)+3х=3
24-6х+3х=3
-6х+3х=3-24
3х=-21
х=-21:3
х=-7

Sin2A = 2sinAcosA; cos2A = 2cos^2A - 1 
sin3A = sin(A+2A) = sinAcos2A + cosAsin2A = sinA(2cos^2A-1) + cosA(2sinAcosA) 
= 2sinAcos^2A - sinA + 2sinAcos^2A 

cos3A = cos(A+2A) = cosAcos2A - sinAsin2A = cosA(2cos^2A-1) - sinA(2sinAcosA) 
= 2cos^3A-cosA - 2sin^2AcosA 

Hence the left side of your equation equals 

(2sinAcosA+4sinAcos^2A) / (2cos^2A - 1 + 2cos^3A - 2sin^2AcosA), now replace sin^2A by 1-cos^2A 

= (2sinAcosA+4sinAcos^2A) / (4cos^3A + 2cos^2A -2cosA - 1) 
= 2sinAcosA(1+2cosA) / ((2cos^2A-1)(1+2cosA)) 
= 2sinAcosA / (2cos^2A - 1) 
= sin2A / cos2A 
= tan2A