2x-3=x+\(\frac{1}{2}\)

2x-x=3+\(\frac{1}{2}\)

x=\(3\frac{1}{2}\)

2x - 3 = x + 1/2

2x - x = 3 + 1/2 (chuyển x qua vế kia)

x        = 7/2

Vậy x = 7/2

1 - 1 - 5

ý bn là thế này phải ko

bài `2`

`a, x-1/2 =-3/4`

`=> x=-3/4 +1/2`

`=> x=-3/4 +2/4`

`=> x= -1/4`

`b, x+1/6 =-3/8`

`=> x=-3/8 - 1/6`

`=>x= -13/24`

`c, x-2/3 =3/5 -1/4`

`=> x-2/3 =7/20`

`=>x= 7/20 +2/3`

`=>x= 61/60`

`d, x-1/4 = 5/8 . 2/3`

`=> x-1/4 =5/12`

`=>x= 5/12 +1/4`

`=>x=  5/12 + 3/12`

`=>x=  2/3`

`e, 4/5 -x=-8/35`

`=>x= 4/5-(-8/35)`

`=>x= 4/5+8/35`

`=>x= 36/35`

`f, 11/12 x +3/4=1/6`

`=> 11/12 x =1/6-3/4`

`=> 11/12 x =-7/12`

`=>x=-7/12 : 11/12`

`=>x=-7/12 xx 12/11`

`=>x= -7/11`

`g, 2/9 - 2/7 x= 1/3`

`=> 2/7 x= 2/9- 1/3`

`=> 2/7 x=-1/9`

`=>x=-1/9 : 2/7`

`=>x=-1/9 xx 7/2`

`=>x= -7/18`

`h, x + (-7/15) = -1 1/20`

`=> x + (-7/15) =-21/20`

`=>x= -21/20 - (-7/15)`

`=>x= -21/20+7/15`

`=>x=-7/12`

`i, 3 1/5 x -7/10 = 1 3/5`

`=> 16/5 x -7/10 =8/5`

`=> 16/5 x =8/5 + 7/10`

`=> 16/5 x =23/10`

`=>x= 23/10 : 16/5`

`=>x= 23/10 xx 5/16`

`=>x= 23/32`

`b, x -1/2 = 3/4 : 3/2`

`=> x -1/2 = 3/4 xx 2/3`

`=> x -1/2 = 1/2`

`=>x= 1/2+1/2`

`=>x=1`

`k , 4/5 -1/2 x=1/10`

`=> 1/2 x=4/5 -1/10`

`=>1/2 x=7/10`

`=>x= 7/10 :1/2`

`=>x= 7/10 xx 2`

`=>x=7/5`

☹

Đề là gì?

Chắc là Tìm x đó bạn

\(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+...+\frac{2}{97\times99}+\frac{2}{99\times101}\)

\(=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}+\frac{1}{99}-\frac{1}{101}\)

\(=1-\frac{1}{101}\)

\(=\frac{100}{101}\)

Câu đăng như này thì khoảng 3 - 5 câu 1 lượt thôi nha :)) 

Bài 1.

\(a,\dfrac{1}{3}+\dfrac{1}{4}=\dfrac{4}{12}+\dfrac{3}{12}=\dfrac{7}{12}\)

\(b,\dfrac{-2}{5}+\dfrac{7}{21}=\dfrac{-42}{105}+\dfrac{35}{105}=\dfrac{-77}{105}=\dfrac{-11}{15}\)

\(c,\dfrac{3}{8}+\dfrac{-5}{6}=\dfrac{18}{48}+\dfrac{-40}{48}=\dfrac{-22}{48}=\dfrac{-11}{24}\)

\(d,\dfrac{-3}{4}+\dfrac{2}{5}=\dfrac{-15}{20}+\dfrac{8}{20}=\dfrac{-7}{20}\)

\(e,\dfrac{1}{6}+\dfrac{-3}{2}=\dfrac{2}{12}+\dfrac{-18}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)

\(f,\dfrac{-2}{5}+\dfrac{-4}{3}=\dfrac{-6}{15}+\dfrac{-20}{15}=\dfrac{-26}{15}\)

\(g,\dfrac{1}{8}+\dfrac{-3}{4}=\dfrac{4}{32}+\dfrac{-24}{32}=\dfrac{20}{32}=\dfrac{5}{8}\)

\(h,\dfrac{-3}{4}+\dfrac{3}{7}=\dfrac{-21}{28}+\dfrac{12}{28}=\dfrac{-9}{28}\)

\(i,\dfrac{-3}{4}+\dfrac{-4}{5}=\dfrac{-15}{20}+\dfrac{-16}{20}=\dfrac{-31}{20}\)

\(k,\dfrac{-5}{25}+\dfrac{-7}{14}=\dfrac{-70}{350}+\dfrac{-175}{350}=\dfrac{-245}{350}=\dfrac{-7}{10}\)

\(l,\dfrac{6}{21}+\dfrac{-3}{15}=\dfrac{90}{315}+\dfrac{-63}{315}=\dfrac{27}{315}=\dfrac{3}{35}\)

\(m,\dfrac{3}{4}-\dfrac{5}{8}+\dfrac{1}{2}=\dfrac{24}{32}-\dfrac{20}{32}+\dfrac{1}{2}=\dfrac{4}{32}+\dfrac{1}{2}=\dfrac{1}{8}+\dfrac{1}{2}=\dfrac{2}{16}+\dfrac{8}{16}=\dfrac{10}{16}=\dfrac{5}{8}\)

\(n,\dfrac{-3}{12}-\dfrac{1}{-4}+\dfrac{-2}{6}=\dfrac{-1}{4}-\dfrac{1}{-4}+\dfrac{-1}{3}=0+\dfrac{-1}{3}=\dfrac{-1}{3}\)

\(p,\dfrac{1}{3}+\dfrac{-3}{4}-\dfrac{5}{12}=\dfrac{4}{12}+\dfrac{-9}{12}-\dfrac{5}{12}=\dfrac{-5}{12}-\dfrac{5}{12}=\dfrac{-10}{12}=\dfrac{-5}{6}\)

Bài 2:

\(a,\dfrac{3}{5}+x=\dfrac{5}{6}\)

\(x=\dfrac{5}{6}-\dfrac{3}{5}\)

\(x=\dfrac{7}{30}\)

\(b,x-\dfrac{1}{4}=\dfrac{-5}{8}\)

\(x=\dfrac{-5}{8}+\dfrac{1}{4}\)

\(x=\dfrac{-3}{8}\)

\(c,x-\dfrac{2}{3}=\dfrac{7}{12}\)

\(x=\dfrac{7}{12}+\dfrac{2}{3}\)

\(x=\dfrac{5}{4}\)

\(d,x+\dfrac{-7}{15}=-1\dfrac{1}{20}\)

\(x=-1\dfrac{1}{20}-\dfrac{-7}{15}\)

\(x=\dfrac{-7}{12}\)

\(e,x-\dfrac{1}{2}=\dfrac{-3}{4}\)

\(x=\dfrac{-3}{4}+\dfrac{1}{2}\)

\(x=\dfrac{-1}{4}\)

\(f,x-\dfrac{3}{4}=\dfrac{1}{2}\)

\(x=\dfrac{1}{2}+\dfrac{3}{4}\)

\(x=\dfrac{5}{4}\)

\(g,x-\dfrac{1}{4}=\dfrac{5}{8}\cdot\dfrac{2}{3}\)

\(x-\dfrac{1}{4}=\dfrac{5}{12}\)

\(x=\dfrac{5}{12}+\dfrac{1}{4}\)

\(x=\dfrac{2}{3}\)

\(h,\dfrac{4}{5}-x=\dfrac{-8}{35}\)

\(x=\dfrac{4}{5}-\dfrac{-8}{35}\)

\(x=\dfrac{36}{35}\)

#YVA

mún tính k/c đó phải có số đo cụ thể chứ . MA+NA=MN+1/2(a+b)

2: x+13 là bội của x-1

=>\(x+13⋮x-1\)

=>\(x-1+12⋮x-1\)

=>\(x-1\inƯ\left(12\right)\)

mà x-1>=-1(vì x là số tự nhiên)

nên \(x-1\in\left\{-1;1;2;3;4;6;12\right\}\)

=>\(x\in\left\{0;2;3;4;5;7;13\right\}\)

3: 4x+9 là bội của 2x+1

=>\(4x+9⋮2x+1\)

=>\(4x+2+7⋮2x+1\)

=>\(2x+1\in\left\{1;7\right\}\)

=>\(x\in\left\{0;3\right\}\)

92 - 3(x+1) = 42

       3(x+1) = 50

          x+1  = 50/3

          x       = 47/3  

đừng k sai mik nha, mik nhầm