=(-259+259)+[(-74)+(-26)]+(-81+581)

=0+(-100)+500

=400

= -259 + 259 - 74 - 26 + 581 + 259 - 81
= 0 - 100 + 840 - 81
= 659

Mình bị nhầm :(( Tại bấm thêm số 259

\(1\frac{13}{15}.0,75-\left(\frac{104}{195}+25\%\right).\frac{24}{47}-3\frac{12}{13}:3\)

\(=\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{8}{9}-\frac{51}{13}.\frac{1}{3}\)

\(=\frac{7}{5}-\left(\frac{32}{60}+\frac{15}{60}\right).\frac{8}{9}-\frac{17}{13}\)

\(=\frac{7}{5}-\frac{47}{60}.\frac{8}{9}-\frac{17}{13}\)

\(=\frac{7}{5}-\frac{94}{135}-\frac{17}{13}\)

\(=\frac{-212}{351}\)

Tự quy đồng

\(2\frac{3}{4}.\left(-0,4\right)-1\frac{3}{5}.2,75+\left(-1,2\right):\frac{4}{11}\)

\(=\frac{11}{4}.\frac{-2}{5}-\frac{8}{5}.\frac{11}{4}-\frac{6}{5}.\frac{11}{4}\)

\(=\frac{11}{4}.\left(\frac{-2}{5}-\frac{8}{5}-\frac{6}{5}\right)\)

\(=\frac{11}{4}.\frac{-16}{5}\)

\(=\frac{-44}{5}=-8\frac{4}{5}\)

\(=2.6\cdot\left(-2\right):2=2.6\cdot\left(-1\right)=-2.6\)

\(\dfrac{3}{7}.\left(\dfrac{-1}{9}\right)+\dfrac{3}{7}.\left(\dfrac{-2}{3}\right)\\ =\dfrac{3}{7}.\left(\dfrac{-1}{9}+\dfrac{-2}{3}\right)\\ =\dfrac{3}{7}.\dfrac{-7}{9}\\ =\dfrac{-21}{63}=\dfrac{-1}{3}\)

\(\dfrac{7}{2}-\left(\dfrac{3}{4}+\dfrac{1}{5}\right)\\ =\dfrac{7}{2}-\left(\dfrac{15}{20}+\dfrac{4}{20}\right)\\ =\dfrac{7}{2}-\dfrac{19}{20}\\ =\dfrac{70}{20}-\dfrac{19}{20}\\ =\dfrac{51}{20}\)

\(\left(\dfrac{1}{3}\right)^2.\dfrac{14}{11}-\dfrac{3}{11}\left(\dfrac{1}{3}\right)^2\\ =\dfrac{1}{9}.\dfrac{14}{11}-\dfrac{3}{11}.\dfrac{1}{9}\\ =\dfrac{1}{9}\left(\dfrac{14}{11}-\dfrac{3}{11}\right)\\ =\dfrac{1}{9}.\dfrac{11}{11}\\ =\dfrac{1}{9}.1\\ =\dfrac{1}{9`}\)

a) = 0,6 - 0,8 = -0,2

b) 1/5 + |-4/5|

= 1/5 + 4/5

= 1

c) 3/7 . (-1/9) + 3/7 . (-2/3) - 5/3

= 3/7 . (-1/9 - 2/3) - 5/3

= 3/7 . 7/9 - 5/3

= 1/3 - 5/3

= -4/3

\(a,\left(\dfrac{3}{8}-\dfrac{1}{5}-\dfrac{1}{3}\right)+\left(\dfrac{5}{8}-1\dfrac{3}{7}-\dfrac{4}{7}\right)+\dfrac{1}{3}\\ =\dfrac{3}{8}-\dfrac{1}{5}-\dfrac{1}{3}+\dfrac{5}{8}-\dfrac{10}{7}-\dfrac{4}{7}\\ =\left(\dfrac{3}{8}+\dfrac{5}{8}\right)-\left(\dfrac{1}{5}+\dfrac{1}{3}-\dfrac{1}{3}\right)-\left(\dfrac{10}{7}+\dfrac{4}{7}\right)\\ =1-\dfrac{1}{5}-2=\left(1-2\right)-\dfrac{1}{5}\\ =-1-\dfrac{1}{5}=-\dfrac{6}{5}\)

\(b,-24\left(\dfrac{1}{3}-\dfrac{1}{4}\right)^2-1,5\\ =-24\left(\dfrac{4}{12}-\dfrac{3}{12}\right)^2-\dfrac{3}{2}\\ =-24\left(\dfrac{1}{12}\right)^2-\dfrac{3}{2}\\ =-24\cdot\dfrac{1}{144}-\dfrac{3}{2}\\ =-\dfrac{2}{37}-\dfrac{3}{2}=\dfrac{4}{74}-\dfrac{111}{74}\\ =\dfrac{-115}{74}\)

ai giúp đi

a) -6/5

b) -115/74