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Kiều Vũ Linh · Accepted Answer

a) $\dfrac{2}{3}:x+\dfrac{1}{3}=-7$$\dfrac{2}{3}:x=-7-\dfrac{1}{3}$$\dfrac{2}{3}:x=-\dfrac{22}{3}$$x=\dfrac{2}{3}:\left(-\dfrac{22}{3}\right)$$x=-\dfrac{1}{11}$b) $\dfrac{31}{16}-\left(\dfrac{1}{3}-x\right)^2=\dfrac{5}{6}$$\left(\dfrac{1}{3}-x\right)^2=\dfrac{31}{36}-\dfrac{5}{6}$$\left(\dfrac{1}{3}-x\right)^2=\dfrac{1}{36}$$\Rightarrow\dfrac{1}{3}-x=\dfrac{1}{6}$ hoặc $\dfrac{1}{3}-x=-\dfrac{1}{6}$*) $\dfrac{1}{3}-x=\dfrac{1}{6}$$x=\dfrac{1}{3}-\dfrac{1}{6}$$x=\dfrac{1}{6}$*) $\dfrac{1}{3}-x=-\dfrac{1}{6}$$x=\dfrac{1}{3}-\left(-\dfrac{1}{6}\right)$$x=\dfrac{1}{2}$Vậy $x=\dfrac{1}{6};x=\dfrac{1}{2}$c) $\dfrac{3}{5}+\dfrac{2}{5}\left(x-2\right)=-\dfrac{8}{5}$$\dfrac{2}{5}\left(x-2\right)=-\dfrac{8}{5}-\dfrac{3}{5}$$\dfrac{2}{5}\left(x-2\right)=-\dfrac{11}{5}$$x-2=-\dfrac{11}{5}:\dfrac{2}{5}$$x-2=-\dfrac{11}{2}$$x=-\dfrac{11}{2}+2$$x=-\dfrac{7}{2}$Câu trả lời: a) $\dfrac{2}{3}:x+\dfrac{1}{3}=-7$$\dfrac{2}{3}:x=-7-\dfrac{1}{3}$$\dfrac{2}{3}:x=-\dfrac{22}{3}$$x=\dfrac{2}{3}:\left(-\dfrac{22}{3}\right)$$x=-\dfrac{1}{11}$b) $\dfrac{31}{16}-\left(\dfrac{1}{3}-x\right)^2=\dfrac{5}{6}$$\left(\dfrac{1}{3}-x\right)^2=\dfrac{31}{36}-\dfrac{5}{6}$$\left(\dfrac{1}{3}-x\right)^2=\dfrac{1}{36}$$\Rightarrow\dfrac{1}{3}-x=\dfrac{1}{6}$ hoặc $\dfrac{1}{3}-x=-\dfrac{1}{6}$*) $\dfrac{1}{3}-x=\dfrac{1}{6}$$x=\dfrac{1}{3}-\dfrac{1}{6}$$x=\dfrac{1}{6}$*) $\dfrac{1}{3}-x=-\dfrac{1}{6}$$x=\dfrac{1}{3}-\left(-\dfrac{1}{6}\right)$$x=\dfrac{1}{2}$Vậy $x=\dfrac{1}{6};x=\dfrac{1}{2}$c) $\dfrac{3}{5}+\dfrac{2}{5}\left(x-2\right)=-\dfrac{8}{5}$$\dfrac{2}{5}\left(x-2\right)=-\dfrac{8}{5}-\dfrac{3}{5}$$\dfrac{2}{5}\left(x-2\right)=-\dfrac{11}{5}$$x-2=-\dfrac{11}{5}:\dfrac{2}{5}$$x-2=-\dfrac{11}{2}$$x=-\dfrac{11}{2}+2$$x=-\dfrac{7}{2}$

HT.Phong (9A5) · Answer

a) $\dfrac{2}{3}:x+\dfrac{1}{3}=-7$$\Rightarrow\dfrac{2}{3}:x=-7-\dfrac{1}{3}$$\Rightarrow\dfrac{2}{3}:x=-\dfrac{22}{3}$$\Rightarrow x=\dfrac{2}{3}:-\dfrac{22}{3}$$\Rightarrow x=-\dfrac{1}{11}$b) $\dfrac{31}{36}-\left(\dfrac{1}{3}-x\right)^2=\dfrac{5}{6}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\dfrac{31}{36}-\dfrac{5}{6}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\dfrac{1}{36}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\left(\dfrac{1}{6}\right)^2$$\Rightarrow\left[{}\begin{matrix}\dfrac{1}{3}-x=\dfrac{1}{6}\\dfrac{1}{3}-x=-\dfrac{1}{6}\end{matrix}\right.$$\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{6}\x=\dfrac{1}{2}\end{matrix}\right.$c) $\dfrac{2}{5}+\dfrac{2}{5}\left(x-2\right)=\dfrac{-8}{5}$$\Rightarrow\dfrac{2}{5}\left(x-2\right)=\dfrac{-8}{5}-\dfrac{2}{5}$$\Rightarrow\dfrac{2}{5}\left(x-2\right)=-2$$\Rightarrow x-2=-2:\dfrac{2}{5}$$\Rightarrow x-2=-5$$\Rightarrow x=-3$Câu trả lời: a) $\dfrac{2}{3}:x+\dfrac{1}{3}=-7$$\Rightarrow\dfrac{2}{3}:x=-7-\dfrac{1}{3}$$\Rightarrow\dfrac{2}{3}:x=-\dfrac{22}{3}$$\Rightarrow x=\dfrac{2}{3}:-\dfrac{22}{3}$$\Rightarrow x=-\dfrac{1}{11}$b) $\dfrac{31}{36}-\left(\dfrac{1}{3}-x\right)^2=\dfrac{5}{6}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\dfrac{31}{36}-\dfrac{5}{6}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\dfrac{1}{36}$$\Rightarrow\left(\dfrac{1}{3}-x\right)^2=\left(\dfrac{1}{6}\right)^2$$\Rightarrow\left[{}\begin{matrix}\dfrac{1}{3}-x=\dfrac{1}{6}\\dfrac{1}{3}-x=-\dfrac{1}{6}\end{matrix}\right.$$\Rightarrow\left[{}\begin{matrix}x=\dfrac{1}{6}\x=\dfrac{1}{2}\end{matrix}\right.$c) $\dfrac{2}{5}+\dfrac{2}{5}\left(x-2\right)=\dfrac{-8}{5}$$\Rightarrow\dfrac{2}{5}\left(x-2\right)=\dfrac{-8}{5}-\dfrac{2}{5}$$\Rightarrow\dfrac{2}{5}\left(x-2\right)=-2$$\Rightarrow x-2=-2:\dfrac{2}{5}$$\Rightarrow x-2=-5$$\Rightarrow x=-3$

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