bài lớp 5 hả

a) 1,5 . x + 15 + x = 31

 (1,5 + 1) . x + 15 = 31

                   2,5 .x = 31 - 15

                  2,5 - x = 16

                         x = 2,5 - 16

                         x =  -13,5

b) (x + 1) + (x + 2) + (x + 3) + ( x + 4) + (x + 5) = 45

  (x + x + x ....+ x) + (1 + 2 + 3 + 4 + 5) = 45

                       5x + 15 = 45

                                5x = 45 - 15

                               5x = 30

                                 x = 6

\(50\%.x+x=52\)

\(\frac{1}{2}x+x=52\)

\(x.\left(\frac{1}{2}+1\right)=52\)

\(x.\left(\frac{1}{2}+\frac{2}{2}\right)=52\)

\(x.\frac{3}{2}=52\)

\(x=52:\frac{3}{2}\)

\(x=52.\frac{2}{3}\)

\(x=\frac{104}{3}\)

Vậy \(x=\frac{104}{3}\)

\(x-\frac{2}{3}-\frac{2}{15}-\frac{2}{35}-\frac{2}{63}=\frac{1}{9}\)

\(x-\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}\right)=\frac{1}{9}\)

\(x-\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}\right)=\frac{1}{9}\)

\(x-\left(1-\frac{1}{9}\right)=\frac{1}{9}\)

\(x-1+\frac{1}{9}=\frac{1}{9}\)

\(x=\frac{1}{9}-\frac{1}{9}+1\)

\(x=1\)

Vậy \(x=1\)

\(\frac{75}{20}-x=\frac{2}{3}.10\)

\(x=\frac{75}{20}-\frac{20}{3}\)

\(x=\frac{225}{60}-\frac{400}{60}\)

\(x=-\frac{175}{60}=-\frac{35}{12}\)

Vậy \(x-\frac{35}{12}\)

a) x + 10 = 20

<=> x = 20 - 10 = 10

Vậy x = 10

b) 2x + 15 = 35

<=> 2x = 35 - 15 = 20

<=> x = 10

Vậy x = 10

c) 3(x + 2) = 15

<=> x + 2 = 15 : 3 = 5

<=> x = 5 - 2 = 3

Vậy x = 3

d) 10x + 15.11 = 20.10

<=> 10x + 165 = 200

<=> 10x = 200 - 165 = 35

<=> x = 35 : 10 = 3,5

Vậy x = 3,5

e) 4(x + 2) = 3.4

<=> x + 2 = 3

<=> x = 3 - 2 = 1

Vậy x = 1

f) 33x + 135 = 26.9

<=> 33x + 135 = 234

<=> 33x = 234 - 135 = 99

<=> x = 99 : 33 = 3

Vậy x = 3

g) 2x + 15 + 16 + 17 = 100

<=> 2x + 48 = 100

<=> 2x = 100 - 48 = 52

<=> x = 52 : 2 = 26

Vậy x = 26

h) 2(x + 9 + 10 + 11) = 4.12.5

<=> x + 30 = 120

<=> x = 120 - 30 = 90

Vậy x = 90

a) \(x+5=20-\left(12-7\right)\)

\(\Rightarrow x+5=20-5\)

\(\Rightarrow x+5=15\)

\(\Rightarrow x=15-5\)

\(\Rightarrow x=10\)

b) \(15-\left(3+2x\right)=2^2\)

\(\Rightarrow3+2x=15-4\)

\(\Rightarrow3+2x=11\)

\(\Rightarrow2x=11-3\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=\dfrac{8}{2}\)

\(\Rightarrow x=4\)

c) \(-11-\left(19-x\right)=50\)

\(\Rightarrow19-x=-11-50\)

\(\Rightarrow19-x=-61\)

\(\Rightarrow x=61+19\)

\(\Rightarrow x=80\)

d) \(159-\left(25-x\right)=43\)

\(\Rightarrow25-x=159-43\)

\(\Rightarrow25-x=116\)

\(\Rightarrow x=25-116\)

\(\Rightarrow x=-91\)

e) \(\left(79-x\right)-43=-\left(17-52\right)\)

\(\Rightarrow\left(79-x\right)-43=52-17\)

\(\Rightarrow79-x-43=35\)

\(\Rightarrow36-x=35\)

\(\Rightarrow x=1\)

f) \(\left(7+x\right)-\left(21-13\right)=32\)

\(\Rightarrow7+x-8=32\)

\(\Rightarrow x-1=32\)

\(\Rightarrow x=32+1\)

\(\Rightarrow x=33\)

g) \(-x+20=-15+8+13\)

\(\Rightarrow-x+20=6\)

\(\Rightarrow x=20-6\)

\(\Rightarrow x=14\)

h) \(-\left(-x+13-142\right)+18=55\)

\(\Rightarrow x-13+142+18=55\)

\(\Rightarrow x+147=55\)

\(\Rightarrow x=55-147\)

\(\Rightarrow x=-92\)

a: =25(15+45*3)

=25*150

=3750

b: \(=-10\left(25+75-50\right)=-10\cdot50=-500\)

c: =>3^x-2=27

=>x-2=3

=>x=5

d: =>2x-5=-4

=>2x=1

=>x=1/2

e: =>2(x-1)^2=32

=>(x-1)^2=16

=>x-1=4 hoặc x-1=-4

=>x=-3 hoặc x=5

f:  =>25(x+3)=75

=>x+3=3

=>x=0

Giải giùm mình câu này   

1) x = UC(36,24) và x 20.

2) x = UC(60, 84, 120) và x≥ 6

3) 91:x;26:x và 10<x<30.

6) x = BC(6,4) và 16 < x <50.

7) x = BC(18, 30, 75) và 0<x<1000.

8) x:10;x:15 và x <100

4) 70:x;84:x và x8.

9) x:20; x:35 và x<500

5) 150:x: 84:x ; 30:x và 0<x<16.

10) x:12; x:21, x:28 và 150≤x≤400

11) (x+21):7; (x+21):8; (x+21):9 vaø 200 <x<

500