tìm x
343 - 4× ( x+1)=143
131+ (26 -3 × x) ÷5 =135
( 4 × x +3) = 4321÷21
1/5×8+1/8×11+1/11×14+......+1/x × (x +3) = 101/1540
nhanh mình tích nha
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Pikachu đơn giản thì làm thử đừng nói mà ko làm nha ^_^
duyệt đi
a) \(\dfrac{5}{8}-\left(x+\dfrac{3}{4}\right)=\dfrac{7}{6}\)
\(-x-\dfrac{3}{4}=\dfrac{13}{24}\)
\(-x=\dfrac{31}{24}\)
\(\Rightarrow x=\dfrac{-31}{24}\)
b) \(\left(x-\dfrac{3}{4}\right)+\dfrac{3}{2}=\dfrac{11}{3}\)
\(x-\dfrac{3}{4}=\dfrac{13}{6}\)
\(x=\dfrac{35}{12}\)
c) \(\left(x+\dfrac{1}{2}\right)-\dfrac{5}{8}=2\)
\(x+\dfrac{1}{2}=\dfrac{21}{8}\)
\(x=\dfrac{17}{8}\)
d) \(\dfrac{11}{2}-\left(\dfrac{4}{5}+x\right)=2-\dfrac{1}{3}\)
\(\dfrac{11}{2}-\left(\dfrac{4}{5}+x\right)=\dfrac{5}{3}\)
\(-\dfrac{4}{5}-x=\dfrac{-23}{6}\)
\(-x=\dfrac{-91}{30}\)
\(\Rightarrow x=\dfrac{91}{30}\)
`5/8-(x+3/4)=7/6`
`=> x+3/4 = 5/8 -7/6`
`=> x+3/4 = -13/24`
`=>x= -13/24 -3/4`
`=>x= -13/24 - 18/24`
`=>x= -31/24`
`-----------`
`(x-3/4)+3/2+11/3`
`=11/3` hả bn?
`----------`
`(x+1/2)-5/8=2`
`=>x+1/2=2+5/8`
`=>x+1/2= 16/8+5/8`
`=> x+1/2=21/8`
`=>x=21/8-1/2`
`=>x= 21/8 - 4/8`
`=>x= 17/8`
`---------`
`11/2-(4/5+x)=2-1/3`
`=> 11/2-(4/5+x)=6/3-1/3`
`=> 11/2-(4/5+x)=5/3`
`=>4/5+x=11/2-5/3`
`=>4/5+x=23/6`
`=>x=23/6-4/5`
`=>x= 91/30`
\(2\left(x-5\right)+3\left(2-3x\right)=5x+7\)
\(\Leftrightarrow2x-10+6-9x=5x+7\)
\(\Leftrightarrow\left(2x-9x\right)+\left(6-10\right)=5x+7\)
\(\Leftrightarrow-7x-4=5x+7\)
\(\Leftrightarrow-7x-5x=4+7\)
\(\Leftrightarrow-12x=11\)
\(\Leftrightarrow x=\frac{-11}{12}\)
\(3x-5\left(x-2\right)+7=4x-12\)
\(\Leftrightarrow3x-5x-10+7=4x-12\)
\(\Leftrightarrow\left(3x-5x\right)-\left(10-7\right)=4x-12\)
\(\Leftrightarrow-2x-3=4x-12\)
\(\Leftrightarrow-2x-4x=3-12\)
\(\Leftrightarrow-6x=-15\)
\(\Leftrightarrow x=\frac{-15}{-6}=\frac{5}{2}\)
\(\frac{1}{5.8}\)+\(\frac{1}{8.11}\)+\(\frac{1}{11.14}\)+........+\(\frac{1}{x.\left(x+3\right)}\)=\(\frac{101}{1540}\)
3(.\(\frac{1}{5.8}+\frac{1}{8.11}\)+\(\frac{1}{11.14}+.......+\frac{1}{x.\left(x+3\right)}=\frac{101}{1540}.3=\frac{303}{1540}\)
\(\frac{3}{5.8}+\frac{3}{8.11}+\frac{3}{11.14}+.....+\frac{3}{x\left(x+3\right)}=\frac{303}{1540}\)
\(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+....+\frac{1}{x}-\frac{1}{x+3}=\frac{303}{1540}\)
\(\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)
\(\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}=\frac{1}{308}\)
=>\(x+3=308\)
\(x=308-3=305\)
Vậy \(x=305\)
\(\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\)
=> \(\frac{1}{3}\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right)=\frac{101}{1540}\)
=> \(\frac{1}{5}-\frac{1}{x+3}=\frac{101}{1540}:\frac{1}{3}\)
=> \(\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)
=> \(\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}\)
=> \(\frac{1}{x+3}=\frac{1}{308}\)
=> x + 3 = 308
x = 308 - 5
x = 303
\(\frac{1}{3}\left(\frac{3}{5\cdot8}+\frac{3}{8\cdot11}+...+\frac{3}{x\left(x+3\right)}\right)=\frac{101}{1540}\)
\(\frac{1}{5}+\frac{1}{8}-\frac{1}{8}+\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}=\frac{101}{1540}:\frac{1}{3}\)
\(\left(\frac{1}{5}-\frac{1}{x+3}\right)+\left(\frac{1}{8}-\frac{1}{8}\right)+...+\left(\frac{1}{x}-\frac{1}{x}\right)=\frac{303}{1540}\)
\(\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)
\(\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}=\frac{1}{308}\)
=>x+3=308
x=308-3
x=305
Vậy x=305
a, (x+2)+(x+5)+(x+8)+(x+11)+(x+14)=75
5x + (2 + 5 + 8 + 11 + 14) = 75
5x + 40 = 75
5x = 35
x = 7
Các câu dưới tương tự.
a)(x+2)+(x+5)+(x+8)+(x+11)+(x+14)=75
x+x+x+x+x+2+5+8+11+14=75
5xx+40=75
5xx=75-40
5xx=35
x=35:5
x=7
b)(x+1)+(x+3)+(x+5)+....+(x+101)=5400
Nhận thấy dãy trên có (101-1):2+1=51(số) nên có 51 x
Tách như câu a
51xx+(1+3+5+...+101)=5400
51xx+[(101+1)x51:2]=5400
51xx+2601=5400
51xx=5400-2601
51xx=2799
x=2799:51
x=933/17
c)(x+1)+(x+4)+(x+7)+....+(x+94)=1840
Phần c này cũng giống phần b,em dựa vào mà làm nhé,giống,khác mỗi số thôi
Chúc em họ tốt^^
\(a;343-4\times\left(x+1\right)=143\)
\(4\times\left(x+1\right)=343-143\)
\(4\times\left(x+1\right)=200\)
\(x+1=200:4\)
\(x+1=50\)
\(x=50-1=49\)
Mấy câu hỏi trẻ trâu thì tự tính nhé
\(\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{x.\left(x+3\right)}=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{3}.\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{x.\left(x+3\right)}\right)=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{3}\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right)=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{3}.\left(\frac{1}{5}-\frac{1}{x+3}\right)=\frac{101}{1540}\)
\(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)
\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{308}\)
\(\Leftrightarrow x+3=308\)
\(\Leftrightarrow x=305\)
Vậy x=305