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Ta có: \(\dfrac{-5}{13}\cdot\dfrac{3}{7}-\dfrac{2}{17}\cdot\dfrac{8}{13}+\dfrac{5}{13}\cdot\dfrac{1}{7}\)
\(=\dfrac{5}{13}\left(-\dfrac{3}{7}+\dfrac{1}{7}\right)-\dfrac{2}{17}\cdot\dfrac{8}{13}\)
\(=\dfrac{5}{13}\cdot\dfrac{-2}{7}-\dfrac{2}{17}\cdot\dfrac{8}{13}\)
\(=\dfrac{-10}{91}-\dfrac{16}{221}\)
\(=\dfrac{-282}{1547}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =>x-3/4=1/6-1/2=1/6-3/6=-2/6=-1/3
=>x=-1/3+3/4=-4/12+9/12=5/12
b: =>x(1/2-5/6)=7/2
=>-1/3x=7/2
hay x=-21/2
c: (4-x)(3x+5)=0
=>4-x=0 hoặc 3x+5=0
=>x=4 hoặc x=-5/3
d: x/16=50/32
=>x/16=25/16
hay x=25
e: =>2x-3=-1/4-3/2=-1/4-6/4=-7/4
=>2x=-7/4+3=5/4
hay x=5/8
![](https://rs.olm.vn/images/avt/0.png?1311)
câu c) mang tính mua vui hay gì hả bn
mếu thật thì x=0,x=số nào cx đc(câu trả lời này mang tính mua vui thôi nhé)
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\(B=\left(1-\dfrac{1}{3}\right)\cdot\left(1-\dfrac{1}{6}\right)\cdot\left(1-\dfrac{1}{10}\right)\cdot\left(1-\dfrac{1}{15}\right)\cdot...\cdot\left(1-\dfrac{1}{780}\right)\)
\(B=\left(1-\dfrac{1}{3+6+10+15+...+780}\right)\)
\(B=\left(1-\dfrac{1}{\left(780-3\right)\div3+1}\right)\)
\(B=\left(1-\dfrac{1}{260}\right)\)
\(B=\dfrac{259}{260}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
`(50% . x+5 1/4) . (-2/3) = 2 5/6`
`(1/2 x + 21/4) . (-2/3) = 17/6`
`1/2 x + 21/4 = -17/4`
`1/2 x = -19/2`
`x=-19`
\(^{^{tham}}\) \(^{^{khảo}}\)
\(\left(50\%.+5\dfrac{1}{4}\right).\left(-\dfrac{2}{3}\right)=2\dfrac{5}{6}\)
\(\left(\dfrac{1}{2}x+\dfrac{21}{2}\right).\left(-\dfrac{2}{3}\right)=\dfrac{17}{6}\)
\(\dfrac{1}{2}x+\dfrac{21}{4}=-\dfrac{17}{4}\)
\(\dfrac{1}{2}x=-\dfrac{19}{2}\)
\(x=-19\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: =>x-3=9
=>x=12
b: =>10-x=-26
=>x=36
c: =>x:4-1=2
=>x:4=3
=>x=12
d: =>x^2=4
=>x=2 hoặc x=-2
e: =>(x-2)^2=100
=>x-2=10 hoặc x-2=-10
=>x=12 hoặc x=-8
Tìm x:
a) (x²-16)(3x+2)=
b) 50% .x + ⅗(x-5) =
c) \(\dfrac{3}{4}+\dfrac{1}{4}:\:x\:=\:-\dfrac{1}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Tìm x
a) 4/5 ( x - 1/3) - \(3\dfrac{1}{2}\)= 50%
b) \(8\dfrac{3}{5}\cdot x-2\dfrac{1}{5}\cdot x=16\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\dfrac{4}{5}\left(x-\dfrac{1}{3}\right)-3\dfrac{1}{2}=50\%\)
\(\dfrac{4}{5}x-\dfrac{4}{15}-\dfrac{7}{2}=\dfrac{1}{2}\)
\(\dfrac{4}{5}x=\dfrac{1}{2}+\dfrac{7}{2}+\dfrac{4}{15}\)
\(\dfrac{4}{5}x=\dfrac{64}{15}\)
\(x=\dfrac{64}{15}:\dfrac{4}{5}\\ x=\dfrac{16}{3}\)
b) \(8\dfrac{3}{5}.x-2\dfrac{1}{5}.x=16\%\)
\(\dfrac{43}{5}x-\dfrac{11}{5}x=\dfrac{4}{25}\)
\(\dfrac{32}{5}x=\dfrac{4}{25}\)
\(x=\dfrac{4}{25}:\dfrac{32}{5}\)
\(x=\dfrac{1}{40}\)
\(\dfrac{2}{3}\cdot x+50\%+x=\dfrac{5}{4}\)
\(\left(\dfrac{2}{3}+1\right)x=\dfrac{5}{4}-\dfrac{1}{2}\)
\(\dfrac{5}{3}x=\dfrac{3}{4}\)
\(x=\dfrac{3}{4}:\dfrac{5}{3}\)
x=\(\dfrac{9}{20}\)