a) 

151 - 2 x ( x-6 ) = 2227 : 17

        2 x ( x-6 ) =   131

        2 x ( x-6 ) =  151 - 131

        2 x ( x-6 ) =    20

               x-6   = 20 : 2

               x - 6 =   10

               x     = 10 + 6

              x      =   16 

b) $\frac{\mathrm{\backslash (\backslash dfrac\{1\}\{3\}\backslash )\; x\; X\; =}}{}$

\(\dfrac{2}{3}-\dfrac{1}{4}=\dfrac{5}{12}\\ X=\dfrac{5}{12}:\dfrac{1}{3}=\dfrac{5}{4}\)

a, 151 - 2 x ( x-6 ) = 2227 : 17

    2 x ( x-6 ) =   131

    2 x ( x-6 ) =  151 - 131

    2 x ( x-6 ) =    20

    x-6   = 20 : 2

    x - 6 =   10

    x = 10 + 6

    x =  16 

a,\(2,5.16,27.4+7,3=16,27.10+7,3=162,7+7,3=170\)

b,\(8.6.10+4.25.12+3.16.31+2.34.24=48.10+48.25+48.31+48.34\)

\(=48.\left(10+25+31+34\right)=48.100=4800\)

c,\(78.31+78.24+78.17+22.72=78\left(31+24+17\right)+22.72=78.72+22.72\)

\(=72.\left(78+22\right)=72.100=7200\)

d,\(102.67-34.51=102.67-17.102=102.\left(67-17\right)=102.50=5100\)

đéo hiểu thì cút nhé đéo ai khiến m trả lời cả . ngu thì nói ngu đi đừng bày đặt t ghét nhất là cái loại như m đấy ạ 

Bài 2 

a, \(1-\left(12,5+x-4,25\right):21,75=0\)

\(=>21,75-12,5-x+4,25=0\)

\(=>13,5-x=0=>x=13,5\)

b,\(x.101-x+72.99+72=21050\)

\(=>100x+72.100=21050\)

\(=>100\left(x+72\right)=21050\)

\(=>x+72=210,5\)\(=>x=138,5\)

c,\(151-2\left(x-6\right)=2227:17\)

\(=>151-2\left(x-6\right)=131\)

\(=>2\left(x-6\right)=20\)

\(=>2x=32=>x=16\)

d,\(\left(x+4\right)+\left(x+6\right)+\left(x+8\right)+...+\left(x+26\right)=210\)\(=>12x+\left(4+6+8+...+26\right)=210\)

\(=>12x+180=210=>12x=30\)

\(=>x=\frac{30}{12}=\frac{15}{6}=\frac{5}{2}\)

ai giup minh lam voi 

a) 100 - 7.(x-5) = 68

 7.(x - 5) = 100 - 68 = 32

    x - 5 = \(\frac{32}{7}\)

     x = \(\frac{32}{7}+5=\frac{67}{7}\)

b) 2(x-6)+2227:17=151

2( x -6) + 131 = 151

2 (x - 6) = 20

x - 6 = 20 : 2 = 10

x = 10 + 6 = 16

a) 11

b) 16

c) 3

d) 5

e) 36

f) 54

g) 5

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

\(x\cdot\frac{22}{9}=\frac{22}{5}-\frac{11}{7}\)

\(x\cdot\frac{22}{9}=\frac{99}{35}\)

\(x=\frac{99}{35}:\frac{22}{9}\)

\(x=\frac{81}{70}\)

Vậy \(x=\frac{81}{70}\).

\(x:\frac{56}{5}=\frac{26}{5}+\frac{52}{5}\)

\(x:\frac{56}{5}=\frac{78}{5}\)

\(x=\frac{78}{5}\cdot\frac{56}{5}\)

\(x=\frac{4368}{25}\)

Vậy \(x=\frac{4368}{25}\).

\(x:\frac{19}{3}=4\)

\(x=4\cdot\frac{19}{3}\)

\(x=\frac{76}{3}\)

Vậy \(x=\frac{76}{3}\).

1/1.2+1/3.4+1/5.6+...+1/49.50

=1/1-1/2+1/3-1/4+...+1/49-1/50

=1/1+1/2+1/3+1/4+...+1/49+1/50-2(1/2+1/4+1/6+...+1/50)

=1/1+1/2+1/3+1/4+...+1/49+1/50-(1/1+1/2+1/3+1/4+...+1/25)

=1/26+1/27+...+1/50=1/26+1/27+...+1/50(đpcm)

b. 1/1-1/2+1/3-1/4+...+1/99-1/100=99/100

7/12=175/300; 5/6=10/12=250/300; 99/100=297/300

(hình như khúc này đề bài sai hả bạn) bạn tự tính ra nhé

bài 2: a.x+1/10+x/12+x/14+...x+1/20

(x+x+x...+x)+(1/10+1/12+...+1/20)

ko có kết quả sao tìm x được bạn:[

b.x+1/2000+x+2/1999=x+3/1998+x+4/1997

x+1/2000+x+2/1999=x+3/1998+x+4/1997

(x+1/2000+1)+(x+2/1999+1)=(x+3/1998+1)+(x+4/1997+1)

x+2002/2000+x+2002/1999=x+2002/1998+x+2002/1997

x+2002(1/2000+1/1999)=(x+2002)(1/1998+1/1997)

=>(1/2000+1/1999)=(1/1998+1/1997)

x+2002(1/2000+1/1999)-(x+2002)(1/1998+1/1997)=0

(x+2002)(1/2000+1/1999-1/1998-1/1997)=0

(x+2002).0=0

(x+2002)=0

x =0-2002=-2002

Chúc bạn học tốt.

Nếu : 

1 x 2 x 3 =5

2 x 3 x 4 = 10 

3 x 4 x 5 = 17

4 x 5 x 6 = 26

Thì 6 x 7 x 8= 50

      k mình nhé ^_^

> Gợi ý: 50

Số giữa nhân số cuối trừ cho số đầu.

1x2x3=5

2x3x4=10

3x4x5=17

4x5x6=26

Thì 6x7x8=50

k mình nhé bn 

a) \(\Leftrightarrow\left|2x-3\right|=\frac{1}{4}\Leftrightarrow\orbr{\begin{cases}x\ge\frac{3}{2}\mid:2x-3=\frac{1}{4}\Rightarrow2x=\frac{13}{4}\Rightarrow x=\frac{13}{8}\left(TM\right)\\x< \frac{3}{2}\mid:3-2x=\frac{1}{4}\Rightarrow2x=\frac{11}{4}\Rightarrow x=\frac{11}{8}\left(TM\right)\end{cases}.}\)

b) \(\Leftrightarrow\left|x-1\right|=\frac{3}{4}\Leftrightarrow\orbr{\begin{cases}x\ge1\mid:x-1=\frac{3}{4}\Rightarrow x=\frac{7}{4}\left(TM\right)\\x< 1\mid:1-x=\frac{3}{4}=>x=\frac{1}{4}\left(TM\right)\end{cases}}\)

c) \(\frac{3}{5\left(x-\frac{5}{6}\right)}-\frac{1}{2\left(\frac{3}{2}-1\right)}=-\frac{1}{4}\Leftrightarrow\frac{3}{\frac{5\left(6x-5\right)}{6}}-\frac{1}{2\cdot\frac{1}{2}}=-\frac{1}{4}\Leftrightarrow\frac{18}{5\left(6x-5\right)}=-\frac{1}{4}+1\)

\(\Leftrightarrow\frac{18}{5\left(6x-5\right)}=\frac{3}{4}\Leftrightarrow6x-5=\frac{24}{5}\Leftrightarrow6x=\frac{49}{5}\Leftrightarrow x=\frac{49}{30}\)

d) \(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)

\(\Leftrightarrow\frac{2}{2\cdot3}+\frac{2}{3\cdot4}+\frac{2}{4\cdot5}+...+\frac{2}{x\left(x+1\right)}=\frac{2015}{2016}\)

\(\Leftrightarrow2\cdot\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2015}{2016}\)

\(\Leftrightarrow2\left(\frac{1}{2}-\frac{1}{x+1}\right)=\frac{2015}{2016}\Leftrightarrow2\cdot\frac{x+1-2}{2\left(x+1\right)}=\frac{2015}{2016}\Leftrightarrow\frac{x-1}{x+1}=\frac{2015}{2016}\)

\(\Leftrightarrow2016x-2016=2015x+2015\Leftrightarrow x=2015+2016=4031\)

Vậy x = 4031.