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Giupf mình với mình cần gấp

Nguyễn Lê Phước Thịnh · Accepted Answer

Bài 4:a: $\dfrac{x}{15}=\dfrac{2}{3}$=>$x=15\cdot\dfrac{2}{3}=10$b: $x+\dfrac{-8}{13}=\dfrac{-21}{13}$=>$x-\dfrac{8}{13}=-\dfrac{21}{13}$=>$x=-\dfrac{21}{13}+\dfrac{8}{13}=-\dfrac{13}{13}=-1$c: $\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}$=>$\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{1}{10}+\dfrac{5}{10}=\dfrac{6}{10}=\dfrac{3}{5}$=>$x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}$d: $\dfrac{3}{4}+\dfrac{1}{4}:x=-3$=>$\dfrac{1}{4}:x=-3-\dfrac{3}{4}=-\dfrac{15}{4}$=>$x=\dfrac{1}{4}:\dfrac{-15}{4}=\dfrac{-1}{15}$e: $\left(\dfrac{2}{3}-x\right)\left(x-\dfrac{1}{4}\right)=0$=>$\left[{}\begin{matrix}\dfrac{2}{3}-x=0\x-\dfrac{1}{4}=0\end{matrix}\right.$=>$\left[{}\begin{matrix}x=\dfrac{2}{3}\x=\dfrac{1}{4}\end{matrix}\right.$f: 0,51-x=-0,35=>x=0,51-(-0,35)=>x=0,51+0,35=0,86Bài 3:a: $-\dfrac{1}{2}+\dfrac{5}{6}+\dfrac{1}{3}$$=\dfrac{-3+5+2}{6}=\dfrac{4}{6}=\dfrac{2}{3}$b: $\dfrac{-3}{8}+\dfrac{7}{4}-\dfrac{1}{12}$$=\dfrac{-9}{24}+\dfrac{42}{24}-\dfrac{2}{24}=\dfrac{31}{24}$c: $\dfrac{3}{5}:\left(\dfrac{1}{4}\cdot\dfrac{7}{5}\right)$$=\dfrac{3}{5}:\dfrac{7}{20}$$=\dfrac{3}{5}\cdot\dfrac{20}{7}=\dfrac{3\cdot4}{7}=\dfrac{12}{7}$d: $\dfrac{10}{11}+\dfrac{4}{11}:4-\dfrac{1}{8}$$=\dfrac{10}{11}+\dfrac{1}{11}-\dfrac{1}{8}$$=1-\dfrac{1}{8}=\dfrac{7}{8}$e: $\dfrac{-5}{7}+\dfrac{8}{11}+\left(-\dfrac{2}{7}\right)+\dfrac{1}{4}+\dfrac{3}{11}$$=\left(-\dfrac{5}{7}-\dfrac{2}{7}\right)+\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{1}{4}$$=-1+1+\dfrac{1}{4}=\dfrac{1}{4}$f: $\dfrac{2}{7}\cdot\dfrac{5}{13}+\dfrac{2}{7}\cdot\dfrac{6}{13}-\dfrac{2}{7}\cdot1\dfrac{11}{13}$$=\dfrac{2}{7}\cdot\left(\dfrac{5}{13}+\dfrac{6}{13}-1-\dfrac{11}{13}\right)$$=\dfrac{2}{7}\cdot\left(-1\right)=-\dfrac{2}{7}$g: $15,3-21,5-3\cdot1,5$=15,3-21,5-4,5=15,3-26=-10,7h: $2\left(4^2-2\cdot4,1\right)+1.25:5$=2(16-8,2)+0,25=15,6+0,25=15,85Câu trả lời: Bài 4:a: $\dfrac{x}{15}=\dfrac{2}{3}$=>$x=15\cdot\dfrac{2}{3}=10$b: $x+\dfrac{-8}{13}=\dfrac{-21}{13}$=>$x-\dfrac{8}{13}=-\dfrac{21}{13}$=>$x=-\dfrac{21}{13}+\dfrac{8}{13}=-\dfrac{13}{13}=-1$c: $\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{1}{10}$=>$\dfrac{2}{3}x=\dfrac{1}{10}+\dfrac{1}{2}=\dfrac{1}{10}+\dfrac{5}{10}=\dfrac{6}{10}=\dfrac{3}{5}$=>$x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}$d: $\dfrac{3}{4}+\dfrac{1}{4}:x=-3$=>$\dfrac{1}{4}:x=-3-\dfrac{3}{4}=-\dfrac{15}{4}$=>$x=\dfrac{1}{4}:\dfrac{-15}{4}=\dfrac{-1}{15}$e: $\left(\dfrac{2}{3}-x\right)\left(x-\dfrac{1}{4}\right)=0$=>$\left[{}\begin{matrix}\dfrac{2}{3}-x=0\x-\dfrac{1}{4}=0\end{matrix}\right.$=>$\left[{}\begin{matrix}x=\dfrac{2}{3}\x=\dfrac{1}{4}\end{matrix}\right.$f: 0,51-x=-0,35=>x=0,51-(-0,35)=>x=0,51+0,35=0,86Bài 3:a: $-\dfrac{1}{2}+\dfrac{5}{6}+\dfrac{1}{3}$$=\dfrac{-3+5+2}{6}=\dfrac{4}{6}=\dfrac{2}{3}$b: $\dfrac{-3}{8}+\dfrac{7}{4}-\dfrac{1}{12}$$=\dfrac{-9}{24}+\dfrac{42}{24}-\dfrac{2}{24}=\dfrac{31}{24}$c: $\dfrac{3}{5}:\left(\dfrac{1}{4}\cdot\dfrac{7}{5}\right)$$=\dfrac{3}{5}:\dfrac{7}{20}$$=\dfrac{3}{5}\cdot\dfrac{20}{7}=\dfrac{3\cdot4}{7}=\dfrac{12}{7}$d: $\dfrac{10}{11}+\dfrac{4}{11}:4-\dfrac{1}{8}$$=\dfrac{10}{11}+\dfrac{1}{11}-\dfrac{1}{8}$$=1-\dfrac{1}{8}=\dfrac{7}{8}$e: $\dfrac{-5}{7}+\dfrac{8}{11}+\left(-\dfrac{2}{7}\right)+\dfrac{1}{4}+\dfrac{3}{11}$$=\left(-\dfrac{5}{7}-\dfrac{2}{7}\right)+\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{1}{4}$$=-1+1+\dfrac{1}{4}=\dfrac{1}{4}$f: $\dfrac{2}{7}\cdot\dfrac{5}{13}+\dfrac{2}{7}\cdot\dfrac{6}{13}-\dfrac{2}{7}\cdot1\dfrac{11}{13}$$=\dfrac{2}{7}\cdot\left(\dfrac{5}{13}+\dfrac{6}{13}-1-\dfrac{11}{13}\right)$$=\dfrac{2}{7}\cdot\left(-1\right)=-\dfrac{2}{7}$g: $15,3-21,5-3\cdot1,5$=15,3-21,5-4,5=15,3-26=-10,7h: $2\left(4^2-2\cdot4,1\right)+1.25:5$=2(16-8,2)+0,25=15,6+0,25=15,85

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