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a, Ta có : \(-\dfrac{3}{2}-2x+\dfrac{3}{4}=-2\)
\(\Rightarrow-2x=-2+\dfrac{3}{2}-\dfrac{3}{4}=-\dfrac{5}{4}\)
\(\Rightarrow x=\dfrac{5}{8}\)
Vậy ...
b, Ta có : \(\left(-\dfrac{2}{3}x-\dfrac{3}{5}\right)\left(-\dfrac{3}{2}-\dfrac{10}{3}\right)=\dfrac{2}{5}\)
\(\Rightarrow-\dfrac{29}{6}\left(-\dfrac{2}{3}x-\dfrac{3}{5}\right)=\dfrac{2}{5}\)
\(\Rightarrow-\dfrac{2}{3}x-\dfrac{3}{5}=-\dfrac{12}{145}\)
\(\Rightarrow-\dfrac{2}{3}x=-\dfrac{12}{145}+\dfrac{3}{5}=\dfrac{15}{29}\)
\(\Rightarrow x=-\dfrac{45}{58}\)
Vậy...
\(2x+\dfrac{5}{3}=\dfrac{-10}{3}\\ 2x=\dfrac{-15}{3}\\ x=\dfrac{-15}{6}\)
Bài 1:
a: \(\left|x\right|=\dfrac{1}{7}\)
b: |x|=1/7
c: \(\left|x\right|=\left|-3\dfrac{1}{5}\right|=\dfrac{16}{5}\)
d: |x|=0
Bài 2
a: \(=-2.853\)
b: \(=7.992\)
`B=-3-2/3+3/5(-10/9-25/3)-5/6`
`=-3-2/3-5/6+3/5(-10/9-50/9)`
`=-3-4/6-5/6+3/5*(-60)/9`
`=-3-9/6-4`
`=-7-3/2=-17/2`
Lời giải:
\(B=-3-\frac{2}{3}+\frac{3}{5}(\frac{-10}{9}-\frac{25}{3})-\frac{5}{6}\)
\(=-3-(\frac{2}{3}+\frac{5}{6})+\frac{3}{5}.(\frac{-10}{9}-\frac{75}{9})\)
\(=-3-\frac{4+5}{6}+\frac{3}{5}.\frac{-85}{9}=-3-\frac{9}{6}-\frac{17}{3}=-(3+\frac{9}{6}+\frac{34}{6})=\frac{-61}{6}\)
Ta có : \(\frac{2^7.3^4}{3^3.2^5}=\frac{2^2.3}{1.1}=4.3=12\)
k cho mk nha!
A = \(\dfrac{2}{3.5}\) + \(\dfrac{2}{5.7}\) + \(\dfrac{2}{7.9}\) + ... + \(\dfrac{2}{19.21}\)
A = \(\dfrac{1}{3}\) - \(\dfrac{1}{5}\) + \(\dfrac{1}{5}\) - \(\dfrac{1}{7}\) + \(\dfrac{1}{7}\) - \(\dfrac{1}{9}\) + ... + \(\dfrac{1}{19}\) - \(\dfrac{1}{21}\)
A = \(\dfrac{1}{3}\) - \(\dfrac{1}{21}\)
A = \(\dfrac{2}{7}\)
=> 5(5+x)=7(3-x)
=>25+5x=21-7x
=>5x+7x=21-25
=>12x= - 4
=>x= -1/3
cảm ơn bạn nha ngọc anh