a: =-5/9-4/9+8/15+7/15-2/11=-2/11

b: =10/17+7/17-5/13-8/13+11/25

=11/25

c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8

d: =(31/10-25/10)*3-2

=3/5*3-2

=9/5-2

=-1/5

a) \(\dfrac{3}{8}+\dfrac{15}{-25}+\dfrac{3}{5}\)

\(=\dfrac{-9}{40}+\dfrac{3}{5}\)

\(=\dfrac{3}{8}\)

b) \(\dfrac{-5}{18}+\dfrac{23}{45}-\dfrac{9}{10}\)

\(=\dfrac{7}{30}-\dfrac{9}{10}\)

\(=\dfrac{-2}{3}\)

c) \(\dfrac{-5}{12}+\dfrac{15}{18}-2,25\)

\(=\dfrac{5}{12}-2,25\)

\(=\dfrac{-11}{6}\)

d) \(\dfrac{5}{6}+\dfrac{2}{3}-0,5\)

\(=\dfrac{3}{2}-0,5\)

\(=1\)

tick cho mink nhé bn ✔

a) \(\dfrac{13}{20}+\dfrac{3}{5}+x=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{5}{4}+x=\dfrac{5}{6}\)

\(\Rightarrow x=\dfrac{5}{6}-\dfrac{5}{4}\)

\(\Rightarrow x=\dfrac{-5}{12}\)

b) \(x+\dfrac{1}{3}=\dfrac{2}{5}-\dfrac{-1}{3}\)

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{11}{15}\)

\(\Rightarrow x=\dfrac{11}{15}-\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{2}{5}\)

c)\(\dfrac{-5}{8}-x=\dfrac{-3}{20}-\dfrac{-1}{6}\)

\(\dfrac{-5}{8}-x=\dfrac{1}{60}\)

\(\Rightarrow x=\dfrac{-5}{8}-\dfrac{1}{60}\)

\(\Rightarrow x=\dfrac{-77}{120}\)

d) \(\dfrac{3}{5}-x=\dfrac{1}{4}+\dfrac{7}{10}\)

\(\Rightarrow\dfrac{3}{5}-x=\dfrac{19}{20}\)

\(\Rightarrow x=\dfrac{3}{5}-\dfrac{19}{20}\)

\(\Rightarrow x=\dfrac{-7}{20}\)

e) \(\dfrac{-3}{7}-x=\dfrac{4}{5}+\dfrac{-2}{3}\)

\(\Rightarrow\dfrac{-3}{7}-x=\dfrac{2}{15}\)

\(\Rightarrow x=\dfrac{-3}{7}-\dfrac{2}{15}\)

\(\Rightarrow x=\dfrac{-59}{105}\)

g) \(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)

\(\Rightarrow\dfrac{-5}{6}-x=\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{-5}{6}-\dfrac{1}{4}\)

\(\Rightarrow x=\dfrac{-13}{12}\)

a) 2/5 < x < 6/5

=> x = 1 ( =5/5 )    (vì x thuộc Z)

Vậy x = 1

b) 3/5 < 3/x < 3/2

=> 5 > x > 2

=> x thuộc { 4 ; 3 }   (vì x thuộc Z)

Vậy ...

c) 3/8 + -11/8 < x < 22/9 + 5/18

=> -8/8 < x < 49/18

=>-1 < x < 2+13/18

=> x thuộc {0; 1; 2}  ( vì x thuộc Z )

Vậy...

có kết quả r mà

a) -1+2-3+4-5+6-....-2015+2016-2017+2018

= (-1+2)+(-3+4)+(-5+6)+.….+(-2015+2016)+(-2017+2018)

= 1+1+1+....+1+1

( Có tất cả 1009 số 1)

= 1009

b)1-2+3-4+5-6+.….+1245-1246+1247-1248

=(1-2)+(3-4)+(5-6)+....+(1245-1246)+(1247-1248)

=-1+(-1)+(-1)+....+(-1)+(-1)

(Có tất cả 624 số (-1))

= -624

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

a: 3/5+1/2=6/10+5/10=11/10

b: 3/2+5/4+5/8=12/8+10/8+5/8=27/8

c: 1/6+4/5+5/2=5/30+24/30+75/30=104/30=52/15

a \(\dfrac{11}{10}\)

b \(\dfrac{27}{8}\)

c \(\dfrac{52}{15}\)

a)\(\dfrac{3}{5}\)+\(\dfrac{1}{2}\)=\(\dfrac{6}{10}\)+\(\dfrac{5}{10}\)

            =\(\dfrac{6+5}{10}\)

            =  \(\dfrac{11}{10}\)

b)\(\dfrac{3}{2}\)+\(\dfrac{5}{4}\)+\(\dfrac{5}{8}\)=\(\dfrac{12}{8}\)+\(\dfrac{10}{8}\)+\(\dfrac{5}{8}\)

                 =\(\dfrac{12+10+5}{8}\)

                 =       \(\dfrac{27}{8}\)

c)\(\dfrac{1}{6}\)+\(\dfrac{4}{5}\)+\(\dfrac{5}{2}\)=\(\dfrac{5}{30}\)+\(\dfrac{24}{30}\)+\(\dfrac{75}{30}\)

                 =\(\dfrac{5+24+75}{30}\)

                 =      \(\dfrac{104}{30}\)

                 =       \(\dfrac{52}{15}\)

Thấy đúng cho 1 tick và 1 follow nhé!

Chúc bạn học tốt!

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