7 x 2 x 5 x 13 - 5 x 2 x 90

=10x91-10x90

=10x(91-90)

=10x1

=10

~~~~~~~~~~~ai đi ngang qua nhớ để lại k ~~~~~~~~~~~~~ 

~~~~~~~~~~~~ Chúc bạn sớm kiếm được nhiều điểm hỏi đáp ~~~~~~~~~~~~~~~~~~~ 

~~~~~~~~~~~ Và chúc các bạn trả lời câu hỏi này kiếm được nhiều k hơn ~~~~~~~~~~~~

7x2x5x13-5x2x90

=(7x13)x(2x5)-(5x2)x90

=91x10-10x90

=910-900

10

7.2.5.13-5.2.90

=(7.13).(5.2)-(5.2).90

=91.10 - 10.90

=10.(91-90)

=10.1

=10

\(\left(5+\frac{4}{7}\right):x=13\)

\(\frac{39}{7}:x=13\)

\(x=\frac{39}{7}:13\)

\(x=\frac{3}{7}\)

\(\left[5+\frac{4}{7}\right]:x=13\)

\(\Rightarrow\left[\frac{5\cdot7+4}{7}\right]:x=13\)

\(\Rightarrow\frac{39}{7}:x=13\)

\(\Rightarrow x=\frac{39}{7}:13=\frac{39}{7}\cdot\frac{1}{13}=\frac{3}{7}\cdot\frac{1}{1}=\frac{3}{7}\)

\(\left[2,8\cdot x+32\right]:\frac{2}{3}=90\)

\(\Rightarrow\left[2,8\cdot x+32\right]=90\cdot\frac{2}{3}\)

\(\Rightarrow\left[2,8\cdot x+32\right]=60\)

\(\Rightarrow2,8\cdot x+32=60\)

\(\Rightarrow2,8\cdot x=60-32\)

\(\Rightarrow2,8\cdot x=28\)

Đến đây dễ rồi :v

\(\left(2,8.x+32\right):\frac{2}{3}=90\)

\(2,8.x+32=90.\frac{2}{3}\)

\(2,8.x+32=60\)

\(2,8.x=60-32\)

\(2,8.x=28\)

\(x=28:2,8\)

\(x=10\)

Tìm x thuộc N biết:

X+245=43×11

=>x+245=473

=>x=228

X-382=159:3

=>x-382=53

=>x=53+382=438

7×X+2×X=918

=>(7+2).x=918

=>9x=918

=>x=918:9=102

3×(X-2)+150=240

=>3.(x-2)=240-150

=>3.(x-2)=90

=>x-2=90:3=30

=>x=30+2=32

(X+13):5=12

=>(x+13)=12.5

=>x+13=60

=>x=60-13

=>x=47

Bấm **** nha

360:(X-7)=90

X+245=43*11

X+245=473

x=473-245

X=228

X-382=159:3

X-382=53

X=382+53

X=435

7*X+2*X=918

(7+2)*X=918

9*X=918

X=918:9

X=102

3*(X-2)+150=240

3*(X-2)=240-150

3*(X-2)=90

X-2=90:3

X-2=30

X=30-2

X=28

(X+13):5=12

X+13=12*5

X+13=60

X=60-13

X=47

360:(X-7)=90

X-7=360:90

X-7=4

X=7+4

X=11

| x + 4 | + 6x = 13

| x + 4 | = 13 - 6x

\(\orbr{\begin{cases}x+4=13-6x\\x+4=-\left(13-6x\right)\end{cases}}\Rightarrow\orbr{\begin{cases}x+6x=13-4\\x+4=-13+6x\end{cases}}\)

\(\orbr{\begin{cases}7x=9\\x-6x=-13-4\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{7}\\-5x=-17\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{9}{7}\\x=\frac{17}{5}\end{cases}}\)

         7.x + 2.x = 927

\(\Leftrightarrow\)( 7 + 2).x =927

\(\Leftrightarrow\)9.x = 927

\(\Leftrightarrow\)x = 927 : 9

\(\Leftrightarrow\)x = 103

Vậy x = 103

          3(x-2)+150=240

\(\Leftrightarrow\)3(x-2)=240-150

\(\Leftrightarrow\)3(x-2)=90

\(\Leftrightarrow\)x-2=90:3

\(\Leftrightarrow\)x-2=30

\(\Leftrightarrow\)x=30+2

\(\Leftrightarrow\)x=32

Vậy x=32

          ( x + 13 ) : 5 = 120

\(\Leftrightarrow\)x + 13 = 120 \(\times\)5

\(\Leftrightarrow\)x + 13 = 600

\(\Leftrightarrow\)x = 600 - 13

\(\Leftrightarrow\)x = 587

Vậy x = 587

          360:(x-7)=90

\(\Leftrightarrow\)x-7=360:90

\(\Leftrightarrow\)x-7=40

\(\Leftrightarrow\)x=40+7

\(\Leftrightarrow\)x=47

Vậy x=47

                                 7.x + 2.x = 927

                                 x.(7 + 2) = 927

                                 x.9 = 927

                                 x = 927 : 9

                                 x = 103

                             Vậy x = 103

                     3(x - 2) + 150 = 240

                    3(x - 2) = 240 - 150

                    3.(x - 2) = 90

                    x - 2 = 90 : 3 = 30

                    x = 30 + 2 = 32

                  Vậy x = 32

                 (x + 13) : 5 = 120

                 x + 13 = 120 x 5 = 600

                x = 600 - 13 = 587

                Vậy x = 587

              360:(x - 7) = 90

                    x - 7 = 360 : 90 = 4

                   x = 4 + 7 = 11

                   Vậy x = 11

             Ủng hộ mk nha !!! ^_^

1: =-2/9(15/17+2/17)=-2/9

2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)

=-2-7/30=-67/30

3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

1: =-2/9(15/17+2/17)=-2/9

2: =34⋅75+97⋅32=34⋅75+97⋅32

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

a)\(\frac{27}{5}\text{x}\frac{91}{12}\text{x}\frac{125}{9}\text{x}\frac{96}{13}=\frac{27}{9}\text{x}\frac{91}{13}\text{x}\frac{125}{5}\text{x}\frac{96}{12}=3\text{x}7\text{x}25\text{x}8\)

Đến đây tự tính nha !

b)\(\frac{2539}{35}\text{x}\frac{7}{90}+\frac{561}{35}\text{x}\frac{7}{90}=\frac{7}{90}\text{x}\left(\frac{2539}{35}+\frac{561}{35}\right)=\frac{7}{90}\text{x}\frac{3100}{35}=\frac{3100}{90}\text{x}\frac{7}{35}=\frac{310}{9}\text{x}\frac{1}{5}=\frac{62}{9}\)

1. 27/5 x 91/12 x 125/9 x 96/13

2. 2539/35 x 7/90 + 561/35 x 7/90

3. 31/7 : (2/5 x 31/7)

4. (29 x 15/23 x 36/29) : 5/23

3)\(\dfrac{31}{7}\) : (\(\dfrac{2}{5}\times\dfrac{31}{7}\) )

=\(\dfrac{31}{7}\) : \(\dfrac{2}{5}\times\dfrac{31}{7}\)

= \(\dfrac{31}{7}:\dfrac{31}{7}\times\dfrac{2}{5}\)

= \(\dfrac{2}{5}\)

4) (\(29\times\dfrac{15}{23}\times\dfrac{31}{7}\)) : \(\dfrac{5}{23}\) 

=\(29\times\dfrac{15}{23}\times\dfrac{31}{7}:\dfrac{5}{23}\)

= \(29\times\dfrac{31}{7}\times\dfrac{15}{23}:\dfrac{5}{23}\)

= 29 x \(\dfrac{31}{7}\times\dfrac{15}{23}\times\dfrac{23}{5}\)

= 29 x \(\dfrac{31}{7}\times3\)

= 29 x 3 x \(\dfrac{31}{7}\) 

= 87 x \(\dfrac{31}{7}\) 

= \(\dfrac{2697}{7}\)

`1, -2/9 xx 15/17 + (-2/9) xx 2/17`

`= -2/9 xx (15/17 + 2/17)`

`= -2/9 xx 17/17`

`=-2/9xx1`

`=-2/9`

__

`-5/3 xx 6/5 + (-7/9) xx 3/10`

`= -30/15 + (-21/90)`

`= -2 + (-7/30)`

`=-60/30 +(-7/30)`

`=-67/30`

__

`15/20 xx 7/5 + (-9/7) xx (-6/4)`

`=3/4 xx7/5 + (-9/7) xx(-6/4)`

`= 21/20 + 54/28`

`= 21/20 + 27/14`

`=417/140`

__

`-25/13 xx 5/19 + (-25/13) xx 14/19`

`=-25/13 xx (5/19 +14/19)`

`=-25/13 xx 19/19`

`= -25/13 xx 1`

`=-25/13`

__

`-7/13 xx 13/5 + (-9/7) xx 5/3`

`=-7/5 +(-15/7)`

`=-124/35`