Ai giúp mik nhé

a: \(=1-\dfrac{7}{10}=\dfrac{3}{10}\)

b: \(=\dfrac{42}{36}+\dfrac{15}{36}-\dfrac{2}{36}-\dfrac{36}{36}=\dfrac{19}{36}\)

c: \(=\dfrac{144}{48}+\dfrac{132}{48}-\dfrac{4}{48}-\dfrac{9}{48}=\dfrac{263}{48}\)

a) \(\left(\frac{-1}{2}\right)+\left|\frac{-7}{6}\right|+\left(\frac{-7}{8}\right)=\frac{-1}{2}+\frac{7}{6}+\left(\frac{-7}{8}\right)=\frac{-5}{24}\)

b) \(\frac{3}{2}.\left|2+x\right|=\frac{5}{4}\)

\(\Rightarrow\left|2+x\right|=\frac{5}{4}:\frac{3}{2}=\frac{5}{6}\)

\(\Rightarrow2+x=\pm\frac{5}{6}\)

\(\Rightarrow\orbr{\begin{cases}2+x=\frac{5}{6}\Rightarrow x=\frac{5}{6}-2=\frac{-7}{6}\\2+x=\frac{-5}{6}\Rightarrow x=\frac{-5}{6}-2=\frac{-17}{6}\end{cases}}\)

Vậy \(x=\left\{\frac{-7}{6};\frac{-17}{6}\right\}\)

c) Ta có: \(\frac{3,7}{x}=\frac{-5}{1,2}\Rightarrow3,7.1,2:\left(-5\right)=x\)

         \(\Rightarrow x=-0,888\)

d) Tự làm

A=(\(\frac{-1}{2}\))+|\(\frac{-7}{6}\)|+(\(\frac{-7}{8}\))

=(\(\frac{-1}{2}\))+\(\frac{-7}{6}\)+(\(\frac{-7}{8}\))

=\(\frac{2}{3}\)+(\(\frac{-7}{8}\))

=\(\frac{-5}{24}\)

Vậy x=\(\frac{-5}{24}\)

B=\(\frac{3}{2}\)x|2+x|=\(\frac{5}{4}\)

=|2+x|=\(\frac{5}{4}\):\(\frac{3}{2}\)

=\(\orbr{\begin{cases}2+x=\frac{5}{6}\\2+x=\frac{-5}{6}\end{cases}}\)

=\(\orbr{\begin{cases}x=\frac{5}{6}-2\\x=\frac{-5}{6}-2\end{cases}}\)

=\(\orbr{\begin{cases}x=-1\frac{1}{6}\\x=-2\frac{5}{6}\end{cases}}\)

Vậy x\(\in\){\(-1\frac{1}{6}\);\(-2\frac{5}{6}\)}

\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+...+\dfrac{1}{110}\)

\(=\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+...+\dfrac{1}{10\times11}\)

\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-...-\dfrac{1}{11}\)

\(=1-\dfrac{1}{11}\)

\(=\dfrac{10}{11}\)

giúp mình với

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18 = 171 nhé

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 + 16 + 17+18.  = 171

\(\dfrac{2}{5}+\dfrac{1}{3}=\dfrac{6+5}{15}=\dfrac{11}{15}\)

\(\dfrac{16}{24}+\dfrac{1}{3}=\dfrac{2}{3}+\dfrac{1}{3}=1\)

\(\dfrac{7}{12}+\dfrac{4}{6}+\dfrac{3}{8}=\dfrac{14}{24}+\dfrac{16}{24}+\dfrac{9}{24}=\dfrac{39}{24}=\dfrac{13}{8}\)

\(1+\dfrac{1}{12}=\dfrac{12+1}{12}=\dfrac{13}{12}\)

2/5+1/3= 6/15+5/15=11/15

2/5+1/3=11/15

16/24+1/3=1

7/12+4/6+3/8=13/8

1+1/12=13/12

\(a.\dfrac{3}{2}+\dfrac{-1}{3}< \dfrac{x}{6}< \dfrac{1}{9}+\dfrac{31}{18}\)

\(\Leftrightarrow\dfrac{7}{6}< \dfrac{x}{6}< \dfrac{11}{6}\)

\(\Leftrightarrow7< x< 11\)

\(\Leftrightarrow x\in\left\{8;9;10\right\}\)

\(b.\dfrac{-5}{12}+\dfrac{7}{12}+\dfrac{-1}{12}< \dfrac{x}{12}< \dfrac{2}{15}+\dfrac{1}{5}\)

\(\Leftrightarrow\dfrac{1}{12}< \dfrac{x}{12}< \dfrac{1}{3}\)

\(\Leftrightarrow\dfrac{1}{12}< \dfrac{x}{12}< \dfrac{4}{12}\)

\(\Leftrightarrow1< x< 4\)

\(\Leftrightarrow x\in\left\{2;3\right\}\)

Bn cộng 2 phân số đó lại

\(1\frac{5}{18}-\frac{5}{18}:\left(\frac{1}{15}+1\frac{1}{12}\right)\)

\(1\frac{5}{18}-\frac{5}{18}:\frac{23}{20}\)

\(1\frac{5}{18}-\frac{23}{20}\)

\(\frac{23}{180}\)

a, \(\frac{3}{10}+\frac{5}{8}=\frac{24}{80}+\frac{50}{80}=\frac{74}{80}=\frac{37}{40}\)

b, \(\frac{1}{8}+\frac{5}{6}=\frac{3}{24}+\frac{20}{24}=\frac{23}{24}\)

c, \(\frac{1}{3}+\frac{1}{6}+\frac{1}{8}=\frac{8}{24}+\frac{4}{24}+\frac{3}{24}=\frac{15}{24}=\frac{5}{8}\)

#Fox