Ответ №1
1)
3х - 8 = 8 - 2х
3х + 2х = 8 + 8
5х = 16
х = 16 : 5
х = 3,2
проверка:
3,2 * 3 - 8 = 8 - 2 * 3,2
9,6 - 8 = 8 - 6,4
1,6 = 1,6
2)
5 + 2х = 3 - 2х
2х + 2х = 3 - 5
4х = - 2
х = - 2 : 4
х = - 0,5
проверка:
5 + 2 * (- 0,5) = 3 - 2 * (- 0,5)
5 - 1 = 3 + 1
4 = 4
3)
2х + 6 = 2 * (3 - х)
2х + 6 = 6 - 2х
2х + 2х = 6 - 6
4х = 0
х = 0 : 4
х = 0
проверка:
2 * 0 + 6 = 2 * (3 - 0)
0 + 6 = 6 - 0
0 = 0
4)
- 5 * (3х + 1) - 11 = - 16
- 15х - 5 - 11 = - 16
- 15 х - 16 = - 16
- 15х = - 16 + 16
- 15х = 0
15х = 0
х = 15 : 0
х = 0
проверка:
- 5 * (3 * 0 + 1) - 11 = - 16
- 5 * (0 + 1) - 11 = - 16
- 5 * 1 - 11 = - 16
- 5 - 11 = - 16
- 16 = - 16
5)
2 * (х + 1) - 3 * (3х + 4) = 0
2х + 2 - 9х - 12 = 0
- 7х - 10 = 0
- 7х = 10
7х = - 10
х = - 10 : 7
х = - 10/7
х = - 1 3/7
проверка:
2 * (- 10/7 + 1) - 3 * (3 * (- 10/7) + 4) = 0
2 * (- 10/7 + 7/7) - 3 * (- 30/7 + 28/7) = 0
2 * (- 3/7) - 3 * (- 2/7) = 0
- 6/7 + 6/7 = 0
0 = 0
6)
5 * (7х + 30) + 2,5 * (10 - 2х) = 1
35х + 150 + 25 - 5х = 1
30х + 175 = 1
30х = 1 - 175
30х = - 174
х = - 174 : 30
х = - 5,8
проверка:
5 * (7 * (- 5,8) + 30) + 2,5 * (10 - 2 * (- 5,8) = 1
5 * (- 40,6 + 30) + 2,5 * (10 + 11,6) = 1
5 * (- 10,6) + 2,5 * 21,6 = 1
- 53 + 54 = 1
1 = 1
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