Tim x biet \(^{x^2}=\frac{4}{5}.\frac{15}{9}\)
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KN
1
MT
20 tháng 9 2015
\(\frac{x+1}{18}+\frac{x+2}{17}=\frac{x+5}{14}+\frac{x+4}{15}\)
\(\Rightarrow\frac{x+1}{18}+1+\frac{x+2}{17}+1=\frac{x+5}{14}+1+\frac{x+4}{15}+1\)
\(\Rightarrow\frac{x+1}{18}+\frac{18}{18}+\frac{x+2}{17}+\frac{17}{17}=\frac{x+5}{14}+\frac{14}{14}+\frac{x+4}{15}+\frac{15}{15}\)
\(\Rightarrow\frac{x+19}{18}+\frac{x+19}{17}=\frac{x+19}{14}+\frac{x+19}{15}\)
\(\Rightarrow\frac{x+19}{18}+\frac{x+19}{17}-\frac{x+19}{14}-\frac{x+19}{15}=0\)
\(\Rightarrow\left(x+19\right).\left(\frac{1}{18}+\frac{1}{17}-\frac{1}{14}-\frac{1}{15}\right)=0\)
\(\text{Mà }\left(\frac{1}{18}+\frac{1}{17}-\frac{1}{14}-\frac{1}{15}\right)\ne0\text{ nên: }x+19=0\Rightarrow x=-19\)
MT
10 tháng 6 2020
c) \(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\)
\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{23}{27}-\frac{5}{9}\)
\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{23}{27}-\frac{15}{27}\)
\(\frac{7}{9}\div\left(2+\frac{3}{4}x\right)=\frac{8}{27}\)
\(2+\frac{3}{4}x=\frac{7}{9}\div\frac{8}{27}\)
\(2+\frac{3}{4}x=\frac{7}{9}.\frac{27}{8}\)
\(2+\frac{3}{4}x=\frac{21}{8}\)
\(\frac{3}{4}x=\frac{21}{8}-2\)
\(\frac{3}{4}x=\frac{21}{8}-\frac{16}{8}\)
\(\frac{3}{4}x=\frac{5}{8}\)
\(x=\frac{5}{8}\div\frac{3}{4}\)
\(x=\frac{5}{8}.\frac{4}{3}\)
\(x=\frac{5}{6}\)
Vậy \(x=\frac{5}{6}\).
d) \(\left|x-\frac{1}{3}\right|-\frac{3}{4}=\frac{5}{3}\)
\(\left|x-\frac{1}{3}\right|=\frac{5}{3}+\frac{3}{4}\)
\(\left|x-\frac{1}{3}\right|=\frac{20}{12}+\frac{9}{12}\)
\(\left|x-\frac{1}{3}\right|=\frac{29}{12}\)
\(\Rightarrow\orbr{\begin{cases}x-\frac{1}{3}=\frac{29}{12}\\x-\frac{1}{3}=-\frac{29}{12}\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{11}{4}\\x=-\frac{25}{12}\end{cases}}\)
Vậy \(x\in\left\{\frac{11}{4};-\frac{25}{12}\right\}\).
R
1
NV
Nguyễn Việt Lâm
Giáo viên
11 tháng 11 2019
\(\frac{x+1,2}{y}=\frac{11}{5}\Rightarrow\frac{x}{y}+\frac{1,2}{y}=\frac{11}{5}\)
\(\Rightarrow\frac{4}{5}+\frac{1,2}{y}=\frac{11}{5}\Rightarrow\frac{1,2}{y}=\frac{7}{5}\Rightarrow y=1,2:\frac{7}{5}=\frac{6}{7}\)
\(\Rightarrow x=\frac{4}{5}y=\frac{4}{5}.\frac{6}{7}=\frac{24}{35}\)
7 tháng 11 2018
a)\(x-\frac{3}{5}=\frac{3}{5}\)
\(\Rightarrow x=\frac{3}{5}+\frac{3}{5}=\frac{6}{5}\)
b)\(|x|-\frac{4}{5}=\frac{2}{3}\\ \Rightarrow|x|=\frac{2}{3}+\frac{4}{5}=\frac{22}{15}\\ \Rightarrow|x|=\frac{22}{15}\\ \Rightarrow x=\frac{22}{15}\)
c)\(\frac{x}{-5}=\frac{24}{15}\\ \Rightarrow x=\frac{-5\cdot24}{15}=-8\)
d)\(\frac{x}{4}=\frac{y}{5} và x-y=21\)
Theo tính chất của dãy tỉ số bằng nhau , ta có :
\(\frac{x}{4}=\frac{y}{5}=\frac{x-y}{4-5}=\frac{21}{-1}=-21\)
Do đó :
\(\frac{x}{4}=-21\Rightarrow x=-84\)
\(\frac{y}{5}=-21\Rightarrow y=-105\)
7 tháng 11 2018
\(x-\frac{3}{5}=\frac{3}{5}\)
\(x=\frac{3}{5}+\frac{3}{5}\)
\(x=\frac{6}{5}\)
\(\left|x\right|-\frac{4}{5}=\frac{2}{5}\)
\(\left|x\right|=\frac{2}{5}+\frac{4}{5}\)
\(\left|x\right|=\frac{6}{5}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{6}{5}\\x=-\frac{6}{5}\end{cases}}\)
\(\frac{x}{-5}=\frac{24}{15}\)
\(\Rightarrow x.15=\left(-5\right).24\)
\(\Rightarrow x.15=-120\)
\(\Rightarrow x=-120:15\)
\(\Rightarrow x=-8\)
18 tháng 5 2020
\(\frac{x+2}{3}=\frac{2x-1}{5}\)
=> \(\left(x+2\right)\cdot5=3\left(2x-1\right)\)
=> \(5x+10=6x-3\)
=> \(6x-5x=10+3\)
=> \(x=13\)
\(\frac{-x}{4}=\frac{-9}{x}\)
=> \(-x^2=4\cdot\left(-9\right)\)
=> \(-x^2=-36\)
=> \(x^2=36\)
=> \(\orbr{\begin{cases}x^2=6^2\\x^2=\left(-6\right)^2\end{cases}}\Rightarrow\orbr{\begin{cases}x=6\\x=-6\end{cases}}\)
18 tháng 5 2020
Quỳnh ơi, chuyển 6x sang sẽ là -6x mà viết như cậu phải là -6x+5x :)
a, \(\frac{x+2}{3}=\frac{2x-1}{5}\)
\(\Leftrightarrow\frac{5x+10}{15}=\frac{6x-3}{15}\Leftrightarrow5x+10=6x-3\Leftrightarrow-x+13=0\Leftrightarrow x=-13\)
b, \(\frac{-x}{4}=\frac{-9}{x}\)\(\Leftrightarrow x^2=36\Leftrightarrow x=\pm6\)
PH
1
12 tháng 6 2020
a, \(2\frac{7}{9}-\frac{12}{13}x=\frac{7}{9}\)
\(\Leftrightarrow\frac{25}{9}-\frac{12}{13}x=\frac{7}{9}\Leftrightarrow\frac{12}{13}x=2\Leftrightarrow x=\frac{13}{6}\)
b, \(\frac{x-12}{4}=\frac{9-3x}{x}\)
\(\Leftrightarrow x^2-12x=36-12x\Leftrightarrow x^2-12x-36+12x=0\)
\(\Leftrightarrow x^2-36=0\Leftrightarrow x^2=36\Leftrightarrow x=\pm6\)
F
1
12 tháng 6 2020
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 : \(x+3=5\Leftrightarrow x=2\)
X=2 NHA