Question

Ai giúp mình bài 4,5 với

Answer 1

Bài 5

a) 1/3 : (x - 1/2) + 5/6 = -3/2

1/3 : (x - 1/2) = -3/2 - 5/6

1/3 : (x - 1/2) = 7/3

x - 1/2 = 1/3 : 7/3

x - 1/2 = 1/7

x = 1/7 + 1/2

x = 3/14

b) (0,16 + 0,01)²x = 0,9

(0,4 + 0,1)²x = 0,9

0,5².x = 0,9

0,25.x = 0,9

x = 0,9 : 0,25

x = 3,6

c) x + (-3/4) : 1 1/8 = 1/3

x - 3/4 : 9/8 = 1/3

x - 2/3 = 1/3

x = 1/3 + 2/3

x = 1

d) (2x - 1)⁴ = 81

(2x - 1)⁴ = 3⁴

2x - 1 = 3 hoặc 2x - 1 = -3

*) 2x - 1 = 3

2x = 4

x = 4 : 2

x = 2

*) 2x - 1 = -3

2x = -2

x = -2 : 2

x = -1

Vậy x = -1; x = 2

Answer 2

Bài 4

a) -1/10 + 2/5 x  + 7/20 = 1/10

2/5 x = 1/10 + 1/10 - 7/20

2/5 x = -3/20

x = -3/20 : 2/5

x = -3/8

b) 1/3 + 1/2 : x = -1/5

1/2 : x = -1/5 - 1/3

1/2 : x = -2/15

x = 1/2 : (-2/15)

x = -15/4

c) -2/3 : x + 5/8 = -7/12

-2/3 : x = -7/12 - 5/8

-2/3 : x = -33/8

x = -2/3 : (-33/8)

x = 16/99

d) 1/2 x + 2 1/2 = 3 1/2 x - 3/4

1/2 x + 5/2 = 7/2 x - 3/4

7/2 x - 1/2 x = 5/2 + 3/4

3x = 13/4

x = 13/4 : 3

x = 13/12

Answer 3

Bài 4

e) 2/3 x - 2/5 = 1/2 x - 1/3

2/3 x - 1/2 x = -1/3 + 2/5

1/6 x = 1/15

x = 1/15 : 1/6

x = 2/5

f) 1/3 x + 2/5 (x + 1) = 0

1/3 x + 2/5 x + 2/5 = 0

11/15 x = -2/5

x = -2/5 : 11/15

x = -6/11

g) 2/3 - 1/3 (x - 3/2) - 1/2 (2x + 1) = 5

2/3 - 1/3 x + 1/2 - x - 1/2 = 5

-4/3 x = 5 - 2/3

-4/3 x = 13/3

x = 13/3 : (-4/3)

x = -13/4

h) (x + 2015)/5 + (x + 2016)/4 = (x + 2017)/3 + (x + 2018)/2

(x + 2015)/5 + 1 + (x + 2016)/4 + 1 = (x + 2017)/3 + 1 + (x + 2018)/2 + 1

(x + 2020)/5 + (x + 2020)/4 = (x + 2020)/3 + (x + 2020)/2

(x + 2020)/5 + (x + 2020)/4 - (x + 2020)/3 - (x + 2020)/2 = 0

(x + 2020).(1/5 + 1/4 - 1/3 - 1/2) = 0

x + 2020 = 0

x = -2020

i) |x + 4/5| - 1/7 = 0

|x + 4/5| = 1/7

x + 4/5 = 1/7 và x + 4/5 = -1/7

*) Với x ≥ -4/5, ta có:

x + 4/5 = 1/7

x = 1/7 - 4/5

x = -23/35 (nhận)

*) Với x < -4/5, ta có:

x + 4/5 = -1/7

x = -1/7 - 4/5

x = -33/35 (nhận)