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làm tiếp cái trước(ấn nhầm)
\(x=\frac{5}{42}-\frac{15}{28}\)
\(x=\frac{5.4}{6.4.7}-\frac{15.6}{4.7.6}\)
\(x=\frac{20}{168}-\frac{90}{168}\)
\(x=\frac{-70}{168}\)
\(x=\frac{-5}{12}\)
2.
1.
\(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)
\(\frac{11}{13}-\frac{5}{42}+x=-\frac{15}{28}+\frac{11}{13}\)
\(\frac{11}{13}-\frac{11}{13}-\frac{5}{42}+\frac{15}{28}=-x\)
a) /x+\(\frac{4}{15}\)/ - / -3,75/ = -2,15
=> \(\orbr{\begin{cases}x+\frac{4}{15}+3,75=-2,15\\x+\frac{4}{15}+3,75=2,15\end{cases}}\)
=> ....v.....v giải ra ( từng th )
bài khác tương tự
|x + 4/15| - |-3,75| = -|- 2,15|
=> |x + 4/15| - 3,75 = 2,15
=> |x + 4/15| = 59/10
=> \(\orbr{\begin{cases}x+\frac{4}{15}=\frac{59}{10}\\x+\frac{4}{15}=-\frac{59}{10}\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{169}{30}\\x=\frac{-185}{30}\end{cases}}\)
\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\left|x+\frac{4}{15}\right|=-2,15+3,75\)
\(\left|x+\frac{4}{15}\right|=1,6\)
\(\left|x+\frac{4}{15}\right|=\frac{8}{5}\)
\(\Rightarrow\hept{\begin{cases}x+\frac{4}{15}=\frac{8}{5}\\x+\frac{4}{15}=\frac{-8}{5}\end{cases}\Rightarrow\hept{\begin{cases}x=\frac{8}{5}-\frac{4}{15}=\frac{4}{3}\\x=\frac{-8}{5}-\frac{4}{15}=\frac{-28}{15}\end{cases}}}\)
a) \(\frac{3}{4}-\left|2x+1\right|=\frac{7}{8}\)
\(\left|2x+1\right|=\frac{3}{4}-\frac{7}{8}\)
\(\left|2x+1\right|=-\frac{1}{8}\)
\(\Rightarrow x\in\varnothing\)
b) \(2.\left|2x-3\right|=\frac{1}{2}\)
\(\left|2x-3\right|=\frac{1}{4}\)
TH1: 2x - 3 = 1/4
...
TH2: 2x -3 = -1/4
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rùi bn tự lm típ nhé! câu c dựa vào phần a;b là lm đk
d)\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\left|x+\frac{4}{15}\right|=1,6\)
...
Bài làm :
Ta có :
\(\left|x+\frac{4}{15}\right|-\left|3,75\right|=-\left|2,15\right|\)
\(\Leftrightarrow\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\Leftrightarrow\left|x+\frac{4}{15}\right|=1,6\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{4}{15}=1,6\\x+\frac{4}{15}=-1,6\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{4}{3}\\x=-\frac{28}{15}\end{cases}}\)
Vậy x=4/3 hoặc x=-28/15
\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\left|x+\frac{4}{15}\right|=1,6\)
\(\Rightarrow\orbr{\begin{cases}x+\frac{4}{15}=1,6\\x+\frac{4}{15}=-1,6\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{4}{3}\\x=\frac{-28}{15}\end{cases}}}\)
Ta có: \(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\Leftrightarrow\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\Leftrightarrow\left|x+\frac{4}{15}\right|=\frac{8}{5}\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{4}{15}=\frac{8}{5}\\x+\frac{4}{15}=-\frac{8}{5}\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=\frac{4}{3}\\x=-\frac{28}{15}\end{cases}}\)
| x + \(\frac{4}{5}\)| - | - 3,75 | = - | - 2,15 |
=> | x + \(\frac{4}{5}\)| - 3,75 = - 2,15
=> | x + \(\frac{4}{5}\)| = 1,6
=> \(\orbr{\begin{cases}x+\frac{4}{5}=1,6\\x+\frac{4}{5}=-1,6\end{cases}}\)
=> \(\orbr{\begin{cases}x=\frac{4}{5}\\x=-\frac{12}{5}\end{cases}}\)
\(\left|x-\frac{4}{15}\right|-\left|-3,75\right|=-2,15\)
\(\left|x-\frac{4}{5}\right|-3,75=-2,15\)
\(\left|x-\frac{4}{5}\right|=-2,15+3,75\)
\(\left|x-\frac{4}{5}\right|=\frac{8}{5}\)
\(\Rightarrow\orbr{\begin{cases}x-\frac{4}{5}=\frac{8}{5}\\x-\frac{4}{5}=-\frac{8}{5}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{12}{5}\\x=-\frac{4}{5}\end{cases}}\)