câu 1
a)\(=-\dfrac{5}{3}+\dfrac{4}{6}=-\dfrac{10}{6}+\dfrac{4}{6}=-\dfrac{6}{6}=-1\)
b)\(=\left(\dfrac{-3}{7}+\dfrac{10}{7}\right)+\left(-\dfrac{4}{9}-\dfrac{23}{9}\right)+\dfrac{2}{3}=1-3+\dfrac{2}{3}=-2+\dfrac{2}{3}=-\dfrac{4}{3}\)
c)\(=\dfrac{9}{4}\cdot\dfrac{7}{2}+\dfrac{9}{4}\cdot\dfrac{7}{16}=\dfrac{9}{4}\cdot\left(\dfrac{7}{2}+\dfrac{7}{16}\right)=\dfrac{9}{4}\cdot\left(\dfrac{56}{16}+\dfrac{7}{16}\right)=\dfrac{9}{4}\cdot\dfrac{63}{16}=\dfrac{567}{64}\)
cây 2
a)\(=>x\left(\dfrac{3}{5}-1\right)=2-\dfrac{1}{3}=\dfrac{6}{3}-\dfrac{1}{3}=\dfrac{5}{5}\)
\(=>x=\dfrac{5}{3}:\left(\dfrac{3}{5}-1\right)=\dfrac{5}{3}:\left(\dfrac{3}{5}-\dfrac{5}{5}\right)=\dfrac{5}{3}:\dfrac{-2}{5}=-\dfrac{25}{6}\)
b)\(x=\dfrac{1}{2}-\dfrac{1}{7}=\dfrac{7}{14}-\dfrac{2}{14}=\dfrac{5}{14}\)
c)\(=>\left[{}\begin{matrix}4x^2=25\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x^2=\dfrac{25}{4}\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-\dfrac{5}{2}\end{matrix}\right.\\x=-3\end{matrix}\right.\)
\(a,-\dfrac{5}{3}+\dfrac{1}{2}:\dfrac{3}{4}=-\dfrac{5}{3}+\dfrac{1}{2}.\dfrac{4}{3}=-\dfrac{5}{3}+\dfrac{2}{3}=-\dfrac{3}{3}=-1\)
\(b,\dfrac{-3}{7}-\dfrac{4}{9}+\dfrac{10}{7}-\dfrac{23}{9}+\dfrac{2}{3}=\left(\dfrac{-3}{7}+\dfrac{10}{7}\right)-\left(\dfrac{4}{9}-\dfrac{23}{9}\right)+\dfrac{2}{3}=1-\left(-2\right)+\dfrac{2}{3}=3+\dfrac{2}{3}=\dfrac{9}{3}+\dfrac{2}{3}=\dfrac{11}{3}\)
\(c,\dfrac{9}{4}:\left(-3,5\right)+\dfrac{9}{4}:2\dfrac{2}{7}=\dfrac{9}{4}:\left(-\dfrac{7}{2}\right)+\dfrac{9}{4}:\dfrac{16}{7}=\dfrac{9}{4}:\left(\dfrac{-7}{2}+\dfrac{16}{7}\right)=\dfrac{9}{4}:\left(\dfrac{-49}{14}+\dfrac{32}{14}\right)=\dfrac{9}{4}:\dfrac{-17}{14}=\dfrac{9}{4}.\dfrac{-14}{17}=-\dfrac{63}{34}\)
