a)

b)

a)

\(\left(\dfrac{9}{25}-2.18\right):\left(3\dfrac{4}{5}+0.2\right)\)

\(=\left(-1.82\right):4=-0.455\)

b) \(\dfrac{5}{18}-1.456:\dfrac{7}{25}+4.5\cdot\dfrac{4}{5}\)

\(=\dfrac{5}{18}-5.2+3.6=-1\dfrac{29}{90}\)

a) \(=-\frac{91}{50}:4\)

   \(=-\frac{91}{200}\)

b) \(=\frac{5}{18}-\frac{26}{5}+\frac{18}{5}\)

   \(=-\frac{119}{90}\)

\(\left(\frac{9}{25}-2,18\right):\left(3\frac{4}{5}+0,2\right)\)

\(=\left(-1,82\right):4\)

\(=-0,455\)

lớp 7???

lớp 6!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

\(\frac{5}{18}-1,456:\frac{7}{25}+4,5.\frac{4}{5}=-\frac{119}{90}\)

a, (\(\frac{9}{25}\) - 2.18) : (\(3\frac{4}{5}\) + 0,2)

 = (\(\frac{9}{25}\) - 36) : 4

 = \(\frac{-891}{25}\) :4

 = -8,91

                                        tạm thời làm tới đây

                                           Chúc bạn học tốt 

a) (925−2.18):(345+0,2)

 = (\(\frac{9}{25}\) - 36) : (\(\frac{19}{5}\) + 0,2)

= \(\frac{-891}{25}\) : 4

= \(\frac{-891}{100}\)

b) 518−1,456:725+4,5.45

 = \(\frac{5}{18}\) - (1,456 : \(\frac{7}{25}\)) + (4,5 . \(\frac{4}{5}\))

= \(\frac{5}{18}\) - \(\frac{26}{5}\) + \(\frac{18}{5}\)

= \(\frac{-443}{90}\) + \(\frac{18}{5}\)

= \(\frac{-119}{90}\).

a) \(\left(\frac{9}{25}-2.18\right):\left(3\frac{4}{5}+0,2\right)\)

\(=\left(\frac{9}{25}-36\right):\left(\frac{19}{5}+0,2\right)\)

\(=\left(-\frac{891}{25}\right):4\)

\(=-\frac{891}{100}\)

b)\(\frac{5}{18}-1,456:\frac{7}{25}+4,5.\frac{4}{5}\)

\(=\frac{5}{18}-\frac{26}{5}+\frac{18}{5}\)

\(=-\frac{119}{90}\)

^...^  ^_^

90. a) \(-\frac{91}{200}\)

b) \(-\frac{119}{90}\)

118. a) >

b) >

c) >

d) =

Bài 90:

Bài 118 SBT:

a) (925−2.18):(345+0,2)(925−2.18):(345+0,2)

=(925−36):(195+15)=(925−36):(195+15)

=(925−90025):205=(925−90025):205

=−89125:4=−89125:4

=−891100=−8,91

a) \(9,2\cdot2\frac{1}{2}-\left(2\cdot0,125-1\frac{5}{12}\right):\frac{1}{4}\)

\(=23-\left(0,25-\frac{17}{12}\right):\frac{1}{4}\)

\(=23-\left(-\frac{7}{6}\right):\frac{1}{4}\)

\(=23-\left(-\frac{14}{3}\right)\)

\(=\frac{83}{3}\)

b) \(\frac{\sqrt{3^2}-\sqrt{39^2}}{\sqrt{59-10-\sqrt{91^2}}}\)

\(=\frac{3-39}{\sqrt{59-10-91}}\)

\(=\frac{-36}{\sqrt{-42}}\)

Vì -42 < 0 \(\Leftrightarrow\)Biểu thức không tồn tại

c) \(\frac{5}{18}-1,456:\frac{7}{25}+4,5\cdot\frac{4}{5}\)

\(=\frac{5}{18}-\frac{26}{5}+\frac{18}{5}\)

\(=\frac{5}{18}-\frac{8}{5}\)

\(=\frac{-119}{90}\)

a)13-18-(-42)-1513-18-(-42)-15

=13-18+42-1513-18+42-15

= (-18-18)+(42+42)+(-1513+13-15)

= -36+84+(-1500-15)

= -36+84+(-1515)

=  48+(-1515)

=  -1467

Thực hiện các phép tính:

a)

b) ;

c)

d) .

Hướng dẫn làm bài:

a)

b) ;

c)

d)

a) \(9,6.2\dfrac{1}{2}-\left(2.125-1\dfrac{5}{12}\right):\dfrac{1}{4}\)

\(=9,6.\dfrac{5}{2}-\left(250-\dfrac{17}{12}\right).4\)

\(=4,8.5-\left(1000-\dfrac{17}{3}\right)\)

\(=24-1000+\dfrac{17}{3}\)

\(=-976+\dfrac{17}{3}=-970\dfrac{1}{3}\)

b) \(\dfrac{5}{18}-1,456:\dfrac{7}{25}+4,5.\dfrac{4}{5}\)

\(=\dfrac{5}{18}-1,456.\dfrac{25}{7}+\dfrac{9}{2}.\dfrac{4}{5}\)

\(=\dfrac{5}{18}-0,208.25+\dfrac{18}{5}\)

\(=\dfrac{5}{18}-5,2+\dfrac{18}{5}\)

\(=-\dfrac{119}{90}\)

c) \(\left(\dfrac{1}{2}+0,8-1\dfrac{1}{3}\right).\left(2,3+4\dfrac{7}{25}-1,28\right)\)

\(=\left(\dfrac{1}{2}+\dfrac{4}{5}-\dfrac{4}{3}\right).\left(\dfrac{23}{10}+\dfrac{107}{25}-\dfrac{32}{25}\right)\)

\(=-\dfrac{1}{30}.\dfrac{265}{50}=-\dfrac{53}{300}\)

d) \(\left(-5\right).12:\left[\left(-\dfrac{1}{4}\right)+\dfrac{1}{2}:\left(-2\right)\right]+1\dfrac{1}{3}\)

\(=-60:\left[\dfrac{1}{4}+\dfrac{1}{2}.\dfrac{-1}{2}\right]+1.\dfrac{1}{3}\)

\(=-60:\left[-\dfrac{1}{4}-\dfrac{1}{4}\right]+1\dfrac{1}{3}\)

\(=-60:\left(\dfrac{1}{2}\right)+1\dfrac{1}{3}\)

\(=121\dfrac{1}{3}\)

a)

b) ;

c)

d)

a) \(\dfrac{4}{5}+\dfrac{3}{15}=\dfrac{4}{5}+\dfrac{1}{5}=\dfrac{5}{5}=1\)

b) \(\dfrac{2}{3}+\dfrac{32}{24}=\dfrac{2}{3}+\dfrac{4}{3}=\dfrac{6}{3}=2\)

c) \(\dfrac{5}{6}+\dfrac{15}{18}=\dfrac{5}{6}+\dfrac{5}{6}=\dfrac{10}{6}=\dfrac{5}{3}\).