Question

Đã trả lời bởi chuyên gia

Answer 1

a) 3x + (-5 + x) = 7 - (5x - 4)

3x - 5 + x = 7 - 5x + 4

4x - 5 = 11 - 5x

4x + 5x = 11 + 5

9x = 16

x = $\frac{16}{9}$

b) 2(x + 5) – 9x = 13 – 4(2x – 3)

2x + 10 - 9x = 13 - 8x + 12

10 - 7x = 25 - 8x

- 7x + 8x = 25 - 10

x = 15

c) 2(x – 3) = 6 – (4 – 4x)

2x - 6 = 6 - 4 + 4x

4x - 2x = - 6 - 6 + 4

2x = - 8

x = - 4

d) x – (3x + 1) = – (x + 1) + 21

x - 3x - 1 = - x - 1 + 21

-2x - 1 = -x + 20

-2x + x = 20 + 1

-x = 21

x = -21

e) $\frac{x - 1}{3} = \frac{x - 2}{2}$

2(x - 1) = 3(x - 2)

2x - 2 = 3x - 6

3x - 2x = -2 + 6

x = 4

f) $\frac{1 - 2 x}{4} = \frac{5 + x}{6}$

6(1 - 2x) = 4(5 + x)

6 - 12x = 20 + 4x

-12x - 4x = 20 - 6

- 16x = 14

x = $\frac{- 7}{8}$

g) $\frac{7 x + 5}{7} = \frac{6 x - 5}{14}$

2(7x + 5) = 6x - 5

14x + 10 = 6x - 5

14x - 6x = -5 - 10

8x = -15

x = $\frac{- 15}{8}$

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Answer 2

a) 3x + (-5 + x) = 7 - (5x - 4)

3x - 5 + x = 7 - 5x + 4

4x - 5 = 11 - 5x

4x + 5x = 11 + 5

9x = 16

x = $\frac{16}{9}$

b) 2(x + 5) – 9x = 13 – 4(2x – 3)

2x + 10 - 9x = 13 - 8x + 12

10 - 7x = 25 - 8x

- 7x + 8x = 25 - 10

x = 15

c) 2(x – 3) = 6 – (4 – 4x)

2x - 6 = 6 - 4 + 4x

4x - 2x = - 6 - 6 + 4

2x = - 8

x = - 4

d) x – (3x + 1) = – (x + 1) + 21

x - 3x - 1 = - x - 1 + 21

-2x - 1 = -x + 20

-2x + x = 20 + 1

-x = 21

x = -21

e) $\frac{x - 1}{3} = \frac{x - 2}{2}$

2(x - 1) = 3(x - 2)

2x - 2 = 3x - 6

3x - 2x = -2 + 6

x = 4

f) $\frac{1 - 2 x}{4} = \frac{5 + x}{6}$

6(1 - 2x) = 4(5 + x)

6 - 12x = 20 + 4x

-12x - 4x = 20 - 6

- 16x = 14

x = $\frac{- 7}{8}$

g) $\frac{7 x + 5}{7} = \frac{6 x - 5}{14}$

2(7x + 5) = 6x - 5

14x + 10 = 6x - 5

14x - 6x = -5 - 10

8x = -15

x = $\frac{- 15}{8}$

Answer 3

`a)`` 3x` + `(-5 + x)` = `7` - `(5x - 4)`
`3x `-` 5` + `x `= `7` - `5x` +` 4`

`4x` - `5` = `11` - `5x`

`4x` + `5x` = `11` +` 5`

`9x` =` 16`

`x `= `16/9`

Vậy `x` =` 16/9`

`b)` `2(x + 5)` -` 9x `= `13` -` 4(2x - 3)`
`2x` + `10` - `9x` = `13` - `8x` + `12`

`-7x` + `10` = `25` - `8x`

`-x `+` 10` = `25`

`x `= `15`

Vậy` x `= `15`

c)` 2(x - 3)` = `6` -` (4 - 4x)`
`2x` -` 6` = `6 `-` 4 `+ `4x`

`2x` - `6` = `2` + `4x`

`2x` - `4x` = `2 `+ `6`

`-2x `= `8`

`x` = `-4`

Vậy `x` = `-4`

d) `x `- `(3x + 1)` = `-(x + 1) `+ `21`
x - 3x - 1 = `-x` - `1` + `21`

`-2x` -` 1 `= `-x `+` 20`

`-2x` + `x `=` 20` +` 1`

`-x `= `21`

`x` = `-21`

Vậy` x` =` -21`

e) x `-` `1/3` = x `-`` 2/2`
`2/2` = 1`

`x` - `1/3` = `x - 1`

Trừ `x` hai vế:

`-1/3` = `-1`

Sai

Phương trình vô nghiệm

`f)` `(1 - 2x)/4` = `5` +` x/6`
Nhân cả `2` vế với` 12`:

`13(1 - 2x)1` = `6`0` + `2x`

`3` - `6x` = `60 `+`2x1`

`-6x `- `2x` =` 60` - `3`

`-8x` = `57`

`x` =` -57/8`

Vậy `x` = `-57/8`

g) `(7x + 5)/7` = `6x` -` 5/14`
Nhân cả` 2 `vế với `14`:

`2(7x + 5) `= `84x` - `5`

`14x` + `10` =` 84x - 5`

`10` +`5` =` 84x - 14x`

`15` = `70x`

`x` =` 15/70 `=` 3/14`

Vậy` x` = `3/14`
#naa.