Bài 1:
a) $\frac{2}{3}-\frac{7}{6}+\frac{3}{4}=$ $\frac{8}{12}-\frac{14}{12}+\frac{9}{12}=$ $\frac{3}{12}$ = $\frac{1}{4}$
b) $(7\frac{4}{5}-1\frac{9}{10})-5\frac{4}{5}=$ $\frac{39}{5}-\frac{19}{10}-$ $\frac{29}{5}=$ $\frac{10}{5}-\frac{19}{10}=$ $\frac{20}{10}-$ $\frac{19}{10}=$ $\frac{1}{10}$
c) $\frac{-11}{23}.\frac{2}{5}+$ $\frac{-12}{23}.$ $\frac{2}{5}-\frac{3}{5}=$ $\frac{2}{5}(\frac{-11}{23}+\frac{-12}{23})-\frac{3}{5}=$ $\frac{2}{5}.\frac{-23}{23}-\frac{3}{5}=$ $\frac{2}{5}.(-1)-\frac{3}{5}=$ $\frac{-2}{5}-\frac{3}{5}=$ $\frac{-5}{5}=-1$
d) $(-\frac{1}{2})^{3}:|-1\frac{3}{8}|-(-2)^3.75$% =$(-\frac{1}{8}):\frac{11}{8}-(-8).\frac{3}{4}=$$\frac{-1}{8}.\frac{8}{11}-(-6)=$$\frac{-1}{11}+6=$$\frac{-1}{11}+\frac{66}{11}=$$\frac{65}{11}$
Bài 2:
a) $-\frac{2}{3}+\frac{3}{4}x=-\frac{5}{6}$
<=> $\frac{3}{4}x=-\frac{5}{6}+\frac{2}{3}$
<=> $\frac{3}{4}x=\frac{-5}{6}+\frac{4}{6}$
<=> $\frac{3}{4}x=\frac{-1}{6}$
<=> $x=\frac{-1}{6}.\frac{4}{3}$
<=> $x=\frac{-2}{9}$
b) $\frac{2}{25}:(2x-1)=(\frac{-1}{5})^2$
<=> $\frac{2}{25}:(2x-1)=\frac{1}{25}$
<=> $2x-1=\frac{1}{25}.\frac{25}{2}$ <=> $2x-1=\frac{1}{2}$
<=> $2x=\frac{1}{2}+1$
<=> $2x=\frac{1}{2}+\frac{2}{2}$
<=> $2x=\frac{3}{2}$
<=> $x=\frac{3}{2}.\frac{1}{2}$
<=> $x=\frac{3}{4}$
Chúc bạn học tốt ^-^
