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Bài 1 :
\(A=\dfrac{\dfrac{3}{7}-\dfrac{3}{17}+\dfrac{3}{37}}{\dfrac{5}{7}-\dfrac{5}{17}+\dfrac{5}{37}}+\dfrac{2}{5}=\dfrac{3\left(\dfrac{1}{7}-\dfrac{1}{17}+\dfrac{1}{37}\right)}{5\left(\dfrac{1}{7}-\dfrac{1}{17}+\dfrac{1}{37}\right)}+\dfrac{2}{5}=\dfrac{3}{5}+\dfrac{2}{5}=\dfrac{5}{5}=1\)
\(a,=\dfrac{5}{7}-\dfrac{33}{8}=-\dfrac{191}{56}\\ b,=\left(\dfrac{12}{17}+\dfrac{5}{17}\right)+\left(\dfrac{19}{7}+\dfrac{3}{7}\right)=1+3=4\\ c,=\left(0,125\cdot8\right)^{12}-\left(\dfrac{45}{15}\right)^3=1-3^3=-26\\ d,=\left(-\dfrac{1}{3}\right)\left(5\dfrac{2}{7}-2\dfrac{2}{7}\right)=-\dfrac{1}{3}\cdot3=-1\\ e,=\dfrac{3^4\cdot3^6}{3^9}=3\)
\(\text{Câu 1 :}\)
\(A=\dfrac{5}{17}+\dfrac{-4}{9}-\dfrac{20}{31}+\dfrac{12}{17}-\dfrac{11}{31}\\ A=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\left(\dfrac{20}{31}+\dfrac{11}{31}\right)+\dfrac{-4}{9}\\ A=1-1+-\dfrac{4}{9}\\ A=-\dfrac{4}{9}\)
\(B=\dfrac{-3}{7}+\dfrac{7}{15}+\dfrac{-4}{7}+\dfrac{8}{15}-\dfrac{-2}{3}\\ B=\left(\dfrac{-3}{7}+\dfrac{-4}{7}\right)+\left(\dfrac{7}{15}+\dfrac{8}{18}\right)-\dfrac{-2}{3}\\ B=\left(-1\right)+1+\dfrac{2}{3}\\ B=\dfrac{2}{3}\)
\(\text{Câu 2 : }\)
\(A< \dfrac{x}{9}\le B\\ \Rightarrow\dfrac{-4}{9}< \dfrac{x}{9}\le\dfrac{2}{3}\\ \Rightarrow\dfrac{-4}{9}< \dfrac{x}{9}\le\dfrac{6}{9}\\ \Rightarrow-4< x\le6\\ \Rightarrow x\in\left\{\pm4;\pm3;\pm2;\pm1;0;5;6\right\}\)
Mk nhầm chút nhé..
x không bằng -4 nhé. Nếu x bằng -4 thì bài sẽ như thế này:
\(-4\le x\le6\)
A=(\(\dfrac{1}{3}-\dfrac{1}{3}\))\(+\left(\dfrac{3}{5}+\left(\dfrac{-3}{5}\right)\right)+\left(\dfrac{-5}{7}+\dfrac{5}{7}\right)+\left(\dfrac{-7}{9}+\dfrac{7}{9}\right)\)\(+\left(\dfrac{-11}{13}-\dfrac{9}{11}\right)\)
A\(=0+0+0+0+\dfrac{-238}{143}\)
A\(=\dfrac{-238}{143}\)
\(B=\left(1+\dfrac{1}{2}\right)+\left(1+\dfrac{1}{4}\right)+\left(1+\dfrac{1}{8}\right)+\left(1+\dfrac{1}{32}\right)+\left(1+\dfrac{1}{64}\right)-7\)
\(B=\left(1+1+1+1+1\right)+\left(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}+\dfrac{1}{64}\right)-7\)
\(B=6+\dfrac{63}{64}-7\)
\(B=-1+\dfrac{63}{64}\)
\(B=\dfrac{-1}{64}\)
b, \(x+\dfrac{2}{3}\) = \(\dfrac{3}{5}\) - \(\dfrac{-1}{6}\)
\(x+\dfrac{2}{3}\) = \(\dfrac{23}{30}\)
\(x\) = \(\dfrac{23}{30}\) - \(\dfrac{2}{3}\)
\(x\) = \(\dfrac{1}{10}\)
a, \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
\(\dfrac{2}{5}+x\) = \(\dfrac{11}{12}-\dfrac{2}{3}\)
\(\dfrac{2}{5}-x\) = \(\dfrac{1}{4}\)
x = \(\dfrac{2}{3}-\dfrac{1}{4}\)
\(x=\dfrac{5}{12}\)
`(-3)/5+7/21+(-4)/5+7/5`
`=(-3)/5+(-4)/5+7/5+7/21`
`=0+7/21=7/21`
`(-3)/17+(2/3+3/17)`
`=(-3)/17+3/17+2/3`
`=0+2/3=2/3`
\(-\dfrac{3}{5}+\dfrac{7}{21}+-\dfrac{4}{5}+\dfrac{7}{5}\)
\(=\left(\dfrac{-3-4+7}{5}\right)+\dfrac{7}{21}=0+\dfrac{7}{21}=\dfrac{7}{21}\)
\(-\dfrac{3}{17}+\left(\dfrac{2}{3}+\dfrac{3}{17}\right)=\left(-\dfrac{3}{17}+\dfrac{3}{17}\right)+\dfrac{2}{3}=0+\dfrac{2}{3}=\dfrac{2}{3}\)
\(a)\dfrac{-5}{21}-\dfrac{1}{3}+3\dfrac{1}{2}.\left(\dfrac{-2}{3}\right)^3\)
\(=\dfrac{-5}{21}+\dfrac{-7}{21}+\dfrac{7}{2}.\dfrac{-8}{27}\)
\(=-\dfrac{4}{7}+\dfrac{-28}{27}\)
\(=\dfrac{-108}{189}+\dfrac{-196}{189}\)
\(=-\dfrac{304}{189}\)
\(b)-2\dfrac{1}{3}+\left(\dfrac{3}{8}-\dfrac{3}{4}\right)^3:\dfrac{5}{9}-\dfrac{1}{2}\)
\(=-\dfrac{7}{3}+\left(\dfrac{3}{8}-\dfrac{6}{8}\right)^3.\dfrac{9}{5}-\dfrac{1}{2}\)
\(=-\dfrac{7}{3}+\left(-\dfrac{3}{8}\right)^3.\dfrac{9}{5}-\dfrac{1}{2}\)
\(=-\dfrac{7}{3}+\dfrac{-27}{512}.\dfrac{9}{5}-\dfrac{1}{2}\)
\(=-\dfrac{7}{3}+\dfrac{-243}{2560}-\dfrac{1}{2}\)
\(=\dfrac{-17920}{7680}+\dfrac{-729}{7680}+\dfrac{-3840}{7680}\)
\(=\dfrac{-22489}{7680}\)