a) x.(-3/7)=5/21 c) -4/7 : x = -2/5 e) 3/4x - 1/2=3/7 g)(2/3x -4/9).(1/2+ -3/7:x)=0
b) x:(-2/5)= -15/16. d) 2/3x + 5/7 = 3/10 f)1/2x + 3/5x =-33/25. h)-4/7 - 5/13.-39/25+-1/42:(-5/6)
i) 2/9.[-4/45:(1/5-2/15)+1\(\frac{2}{3}\) ] - -5/27
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a) | 5/4x -7/2| - | 5/8x + 3/5| = 0
|5/4x - 7/2| = | 5/8x + 3/5|
TH1: 5/4x - 7/2 = 5/8x + 3/5
=> 5/4x - 5/8x = 3/5 +7/2
5/8x = 41/10
x = 41/10:5/8
x = 164/25
TH2: 5/4x - 7/2 = -5/8x - 3/5
=> 5/4x + 5/8x = -3/5 +7/2
15/8x = 29/10
x = 29/10 : 15/8
x = 116/75
KL: x = 164/25 hoặc x = 116/75
các bài cn lại b lm tương tự nha! h lm dài lắm!
a: =>|5/4x-7/2|=|5/8x+3/5|
=>5/4x-7/2=5/8x+3/5 hoặc 5/4x-7/2=-5/8x-3/5
=>5/8x=41/10 hoặc 15/8x=29/10
=>x=164/25 hoặc x=116/75
b: =>3:|x/4-2/3|=6-21/5=9/5
=>|1/4x-2/3|=5/3
=>1/4x-2/3=5/3 hoặc 1/4x-2/3=-5/3
=>1/4x=7/3 hoặc 1/4x=-1
=>x=28/3 hoặc x=-4
c: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(2x-x-9\right)\left(2x+x+9\right)=0\end{matrix}\right.\Leftrightarrow x=9\)
e: =>|2x-7|=2x-7
=>2x-7>=0
=>x>=7/2
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
a) \(\frac{2}{5}+x=\frac{3}{4}\)
\(x=\frac{3}{4}-\frac{2}{5}\)
\(x=\frac{15}{20}-\frac{8}{20}\)
\(x=\frac{7}{20}\)
\(\)b)
\(x-\frac{1}{15}=\frac{3}{10}\\ x=\frac{3}{10}+\frac{1}{15}\\ x=\frac{9}{30}+\frac{2}{30}\\ x=\frac{11}{30}\)
c)
\(\frac{9}{8}-x=\frac{5}{12}\\ x=\frac{9}{8}-\frac{5}{12}\\ x=\frac{27}{24}-\frac{10}{24}\\ x=\frac{17}{24}\)
d)
\(\frac{3}{5}+x=\frac{5}{4}+\frac{7}{10}\\ \frac{3}{5}+x=\frac{25}{20}+\frac{14}{20}\\\frac{3}{5}+x=\frac{39}{20}\\ x=\frac{39}{20}-\frac{3}{5}\\ x=\frac{39}{20}-\frac{12}{20}\\ x=\frac{27}{20} \)
e)
\(\frac{9}{8}-x=\frac{3}{20}+\frac{2}{5}\\ \frac{9}{8}-x=\frac{3}{20}+\frac{8}{20}\\ \frac{9}{8}-x=\frac{11}{20}\\ x=\frac{9}{8}-\frac{11}{20}\\ x=\frac{45}{40}-\frac{22}{40}\\ x=\frac{23}{40}\)
g)
\(x+\frac{1}{3}=\frac{5}{6}+1\frac{7}{10}\\ x+\frac{1}{3}=\frac{5}{6}+\frac{17}{10}\\ x+\frac{1}{3}=\frac{25}{30}+\frac{51}{30}\\ x+\frac{1}{3}=\frac{76}{30}=\frac{38}{15}\\ x=\frac{38}{15}-\frac{1}{3}\\ x=\frac{38}{15}-\frac{5}{15}\\ x=\frac{33}{15}=\frac{11}{5}\)
h)
\(3x-\frac{3}{5}=\frac{1}{2}\\ 3x=\frac{1}{2}+\frac{3}{5}\\ 3x=\frac{5}{10}+\frac{6}{10}\\ 3x=\frac{11}{10}\\ x=\frac{11}{10}:3\\ x=\frac{11}{10}\cdot\frac{1}{3}\\ x=\frac{11}{30}\)
i)
\(4x+\frac{5}{12}+\frac{4}{9}=1\frac{13}{18}\\ 4x+\frac{5}{12}+\frac{4}{9}=\frac{31}{18}\\ 4x+\frac{5}{12}=\frac{31}{18}-\frac{4}{9}\\ 4x+\frac{5}{12}=\frac{31}{18}-\frac{8}{18}\\ 4x+\frac{5}{12}=\frac{23}{18}\\ 4x=\frac{23}{18}-\frac{5}{12}\\ 4x=\frac{46}{36}-\frac{15}{36}\\ 4x=\frac{31}{36}\\ x=\frac{31}{36}:4\\ x=\frac{31}{36}\cdot\frac{1}{4}\\ x=\frac{31}{144}\)
k)
\(2-\left(3x+\frac{3}{7}\right)=\frac{9}{21}\\ 2-\left(3x+\frac{3}{7}\right)=\frac{3}{7}\\3x+\frac{3}{7}=2-\frac{3}{7}\\ 3x+\frac{3}{7}=\frac{14}{7}-\frac{3}{7}\\ 3x+\frac{3}{7}=\frac{11}{7}\\ 3x=\frac{11}{7}-\frac{3}{7}\\ 3x=\frac{8}{7}\\ x=\frac{8}{7}:3\\ x=\frac{8}{7}\cdot\frac{1}{3}\\ x=\frac{8}{21} \)
\(a,x\left(-\frac{3}{7}\right)=\frac{5}{21}\)
\(\Rightarrow x=\frac{5}{21}:\left(-\frac{3}{7}\right)\)
\(\Rightarrow x=-\frac{5}{9}\)
\(b,x:\left(-\frac{2}{5}\right)=-\frac{15}{16}\)
\(\Rightarrow x=-\frac{15}{16}.\left(-\frac{2}{5}\right)\)
\(\Rightarrow x=\frac{3}{8}\)
\(c,-\frac{4}{7}:x=-\frac{2}{5}\)
\(\Rightarrow x=-\frac{4}{7}:\left(-\frac{2}{5}\right)\)
\(\Rightarrow x=\frac{10}{7}\)
\(d,\frac{2}{3}x+\frac{5}{7}=\frac{3}{10}\)
\(\frac{\Rightarrow2}{3}x=\frac{3}{10}-\frac{5}{7}\)
\(\Rightarrow\frac{2}{3}x=-\frac{29}{70}\)
\(\Rightarrow x=-\frac{29}{70}:\frac{2}{3}\)
\(\Rightarrow x=-\frac{87}{140}\)
a, \(x.\left(-\frac{3}{7}\right)=\frac{5}{21}\)
\(\Rightarrow x=\frac{5}{21}:\left(-\frac{3}{7}\right)\)
\(\Rightarrow x=-\frac{5}{9}\)
b, \(x:\left(-\frac{2}{5}\right)=\left(-\frac{15}{16}\right)\)
\(\Rightarrow x=\left(-\frac{15}{16}\right).\left(-\frac{2}{5}\right)\)
\(\Rightarrow x=\frac{5}{8}\)
c, \(\left(-\frac{4}{7}\right):x=-\frac{2}{5}\)
\(x=\left(-\frac{4}{7}\right):\left(-\frac{2}{5}\right)\)
\(\Rightarrow x=\frac{10}{7}\)
d, \(\frac{2}{3}x+\frac{5}{7}=\frac{3}{10}\)
\(\Rightarrow\frac{2}{3}x=\frac{3}{10}-\frac{5}{7}\)
\(\Rightarrow\frac{2}{3}x=-\frac{29}{70}\)
\(\Rightarrow x=-\frac{29}{70}:\frac{2}{3}\)
\(\Rightarrow x=-\frac{87}{140}\)
e, \(\frac{3}{4}x-\frac{1}{2}=\frac{3}{7}\)
\(\Rightarrow\frac{3}{4}x=\frac{3}{7}+\frac{1}{2}\)
\(\Rightarrow\frac{3}{4}x=\frac{13}{14}\)
\(\Rightarrow x=\frac{13}{14}:\frac{3}{4}\)
\(\Rightarrow x=\frac{26}{21}\)
f, \(\frac{1}{2}x+\frac{3}{5}x=-\frac{33}{25}\)
\(\Rightarrow x\left(\frac{1}{2}+\frac{3}{5}\right)=-\frac{33}{25}\)
\(\Rightarrow\frac{11}{10}x=-\frac{33}{25}\)
\(\Rightarrow x=-\frac{33}{25}:\frac{11}{10}\)
\(\Rightarrow x=-\frac{6}{5}\)
g, \(\left(\frac{2}{3}x-\frac{4}{9}\right)\left(\frac{1}{2}+\left(-\frac{3}{7}\right):x\right)=0\)
\(\orbr{\begin{cases}\frac{2}{3}x-\frac{4}{9}=0\\\frac{1}{2}+-\frac{3}{7}:x=0\end{cases}\Rightarrow\orbr{\begin{cases}\frac{2}{3}x=\frac{4}{9}\\-\frac{3}{7}:x=-\frac{1}{2}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{4}{9}:\frac{2}{3}\\x=-\frac{3}{7}:-\frac{1}{2}\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{2}{3}\\x=\frac{6}{7}\end{cases}}}\)
h, \(-\frac{4}{7}-\frac{5}{13}.-\frac{39}{25}+-\frac{1}{42}:-\frac{5}{6}=-\frac{4}{7}+\frac{3}{5}+\frac{1}{35}\)
\(=\frac{-20+21+1}{35}=\frac{2}{35}\)
i, \(\frac{2}{9}\left[-\frac{4}{45}:\left(\frac{1}{5}-\frac{2}{15}\right)+1\frac{2}{3}\right]--\frac{5}{27}=\frac{2}{9}\left(-\frac{4}{45}:\frac{3-2}{15}+\frac{5}{3}\right)+\frac{5}{27}\)
\(=\frac{2}{9}\left(-\frac{4}{45}.15+\frac{5}{3}\right)+\frac{5}{27}=\frac{2}{9}\left(-\frac{4}{3}+\frac{5}{3}\right)+\frac{5}{27}\)
\(=\frac{2}{9}.\frac{1}{3}+\frac{5}{27}=\frac{2}{27}+\frac{5}{27}=\frac{7}{27}\)