Tim x biet
a) \(\frac{x}{3}-\frac{1}{4}=\frac{-5}{6}\)
b) \(\frac{x+3}{15}=\frac{1}{3}\)
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8 tháng 7 2017
\(\frac{x+2015}{5}+\frac{x+2016}{4}=\frac{x+2017}{3}+\frac{x+2018}{2}\)
\(\Leftrightarrow\left(\frac{x+2015}{5}+1\right)+\left(\frac{x+2016}{4}+1\right)=\left(\frac{x+2017}{3}+1\right)+\left(\frac{x+2018}{2}+1\right)\)
\(\Leftrightarrow\frac{x+2020}{5}+\frac{x+2020}{4}-\frac{x+2020}{3}-\frac{x+2020}{2}=0\)
\(\Leftrightarrow\left(x+2020\right)\left(\frac{1}{5}+\frac{1}{4}-\frac{1}{3}-\frac{1}{2}\right)=0\)
\(\Leftrightarrow x+2020=0\)vì \(\frac{1}{5}+\frac{1}{4}+\frac{1}{3}+\frac{1}{2}\ne0\)
\(\Leftrightarrow x=-2020\)
14 tháng 3 2020
a)\(\frac{\frac{x-3}{5}+1}{4}=\frac{\frac{2x}{3}-\frac{1}{2}}{6}\)
\(\Rightarrow\frac{\frac{x-3+5}{5}}{4}=\frac{\frac{4x}{6}-\frac{3}{6}}{6}\)
\(\Rightarrow\frac{\frac{x+2}{5}}{4}=\frac{\frac{4x-3}{6}}{6}\)
\(\Rightarrow\frac{x+2}{5}:4=\frac{4x-3}{6}:6\)
\(\Rightarrow\frac{x+2}{5}.\frac{1}{4}=\frac{4x-3}{6}.\frac{1}{6}\)
\(\Rightarrow\frac{x+2}{20}=\frac{4x-3}{36}\)
\(\Rightarrow36.\left(x+2\right)=20.\left(4x-3\right)\)
\(\Rightarrow36x+72=80x-60\)
\(\Rightarrow72+60=80x-36x\)
\(\Rightarrow132=44x\)
\(\Rightarrow x=\frac{132}{44}=3\)
Vậy x=3
b)Bn làm tương tự phần a nha
Chúc bn học tốt
14 tháng 3 2020
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Chúc bn học tốt
LT
14 tháng 3 2020
\(\Leftrightarrow\frac{3x-3+5}{20}=|\frac{4x-3}{36}|\)
\(\Leftrightarrow\frac{3x+2}{5}=|\frac{4x-3}{9}|\)
\(\Leftrightarrow\left(3x+2\right)9=5|4x-3|\)
ĐK: \(3x+2\ge0\Rightarrow x\ge\frac{-2}{3}\)
\(\Leftrightarrow\orbr{\begin{cases}5.\left(4x-3\right)=9.\left(3x+2\right)\\-5.\left(4x-3\right)=9.\left(3x+2\right)\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}20x-15=27x+18\\-20x+15=27x+18\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}7x=-33\\-47x=3\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{-33}{7}\left(L\right)\\x=\frac{-3}{47}\end{cases}}}\)
Vậy x= - 3/47
b) \(\Leftrightarrow\frac{10x+x+2}{18}=\frac{x+3+75}{60}-2\)
\(\Leftrightarrow\frac{11x+2}{18}=\frac{x-42}{60}\)
\(\Leftrightarrow10.\left(11x+2\right)=3.\left(x-42\right)\)
\(\Leftrightarrow110x+20=3x-126\)
\(\Leftrightarrow107x=-146\Leftrightarrow x=\frac{-146}{107}\)
15 tháng 3 2019
\(a)\frac{1}{3}+\frac{-2}{5}+\frac{1}{6}+\frac{-1}{5}\le x< \frac{-3}{4}+\frac{2}{7}+\frac{-1}{4}+\frac{3}{5}+\frac{5}{7}\)
\(\Rightarrow\frac{1}{3}+\frac{1}{6}+\frac{-2}{5}+\frac{-1}{5}\le x< \frac{-3}{4}+\frac{-1}{4}+\frac{2}{7}+\frac{5}{7}+\frac{3}{5}\)
\(\Rightarrow\frac{2}{6}+\frac{1}{6}+\frac{-3}{5}\le x< -1+1+\frac{3}{5}\)
\(\Rightarrow\frac{1}{2}+\frac{-3}{5}\le x< \frac{3}{5}\)
\(\Rightarrow\frac{-1}{10}\le x< \frac{6}{10}\)
\(\Rightarrow-1\le x< 6\)
\(\Rightarrow x\in\left\{-1;0;1;2;3;4;5\right\}\)
Bài b tương tự
a, \(\frac{x}{3}-\frac{1}{4}=-\frac{5}{6}\Leftrightarrow\frac{x}{3}+\frac{7}{12}=0\Leftrightarrow\frac{4x}{12}+\frac{7}{12}=0\)
Khử mẫu ta đc : \(4x+7=0\Leftrightarrow4x=-7\Leftrightarrow x=-\frac{7}{4}\)
b, \(\frac{x+3}{15}=\frac{1}{3}\Leftrightarrow\frac{x+3}{15}=\frac{5}{15}\)
Khử mẫu ta đc : \(x+3=5\Leftrightarrow x=2\)