Tính hợp lý ; 2/11 - 3/8 + 4/11 - 6/11 -5/8
Kết quả phép tính ; -2020/2021 x 9/11 + -2020/2021 x 2/11
Tìm số nguyên y bt ; 2/-3 = 6/-y
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=(-259+259)+[(-74)+(-26)]+(-81+581)
=0+(-100)+500
=400
= -259 + 259 - 74 - 26 + 581 + 259 - 81
= 0 - 100 + 840 - 81
= 659
\(1\frac{13}{15}.0,75-\left(\frac{104}{195}+25\%\right).\frac{24}{47}-3\frac{12}{13}:3\)
\(=\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{8}{9}-\frac{51}{13}.\frac{1}{3}\)
\(=\frac{7}{5}-\left(\frac{32}{60}+\frac{15}{60}\right).\frac{8}{9}-\frac{17}{13}\)
\(=\frac{7}{5}-\frac{47}{60}.\frac{8}{9}-\frac{17}{13}\)
\(=\frac{7}{5}-\frac{94}{135}-\frac{17}{13}\)
\(=\frac{-212}{351}\)
Tự quy đồng
\(2\frac{3}{4}.\left(-0,4\right)-1\frac{3}{5}.2,75+\left(-1,2\right):\frac{4}{11}\)
\(=\frac{11}{4}.\frac{-2}{5}-\frac{8}{5}.\frac{11}{4}-\frac{6}{5}.\frac{11}{4}\)
\(=\frac{11}{4}.\left(\frac{-2}{5}-\frac{8}{5}-\frac{6}{5}\right)\)
\(=\frac{11}{4}.\frac{-16}{5}\)
\(=\frac{-44}{5}=-8\frac{4}{5}\)
\(=2.6\cdot\left(-2\right):2=2.6\cdot\left(-1\right)=-2.6\)
\(\left(\dfrac{1}{3}\right)^2.\dfrac{14}{11}-\dfrac{3}{11}\left(\dfrac{1}{3}\right)^2\\ =\dfrac{1}{9}.\dfrac{14}{11}-\dfrac{3}{11}.\dfrac{1}{9}\\ =\dfrac{1}{9}\left(\dfrac{14}{11}-\dfrac{3}{11}\right)\\ =\dfrac{1}{9}.\dfrac{11}{11}\\ =\dfrac{1}{9}.1\\ =\dfrac{1}{9`}\)
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
\(a,\left(\dfrac{3}{8}-\dfrac{1}{5}-\dfrac{1}{3}\right)+\left(\dfrac{5}{8}-1\dfrac{3}{7}-\dfrac{4}{7}\right)+\dfrac{1}{3}\\ =\dfrac{3}{8}-\dfrac{1}{5}-\dfrac{1}{3}+\dfrac{5}{8}-\dfrac{10}{7}-\dfrac{4}{7}\\ =\left(\dfrac{3}{8}+\dfrac{5}{8}\right)-\left(\dfrac{1}{5}+\dfrac{1}{3}-\dfrac{1}{3}\right)-\left(\dfrac{10}{7}+\dfrac{4}{7}\right)\\ =1-\dfrac{1}{5}-2=\left(1-2\right)-\dfrac{1}{5}\\ =-1-\dfrac{1}{5}=-\dfrac{6}{5}\)
\(b,-24\left(\dfrac{1}{3}-\dfrac{1}{4}\right)^2-1,5\\ =-24\left(\dfrac{4}{12}-\dfrac{3}{12}\right)^2-\dfrac{3}{2}\\ =-24\left(\dfrac{1}{12}\right)^2-\dfrac{3}{2}\\ =-24\cdot\dfrac{1}{144}-\dfrac{3}{2}\\ =-\dfrac{2}{37}-\dfrac{3}{2}=\dfrac{4}{74}-\dfrac{111}{74}\\ =\dfrac{-115}{74}\)
a) (-124) + 24 = -100
b) 37. 78 + 37. 22
= 37 . ( 78 + 22 )
= 37 . 100
= 3700
a:
\(\dfrac{2}{11}-\dfrac{3}{8}+\dfrac{4}{11}-\dfrac{6}{11}-\dfrac{5}{8}\)
\(=\left(\dfrac{2}{11}+\dfrac{4}{11}-\dfrac{6}{11}\right)+\left(-\dfrac{3}{8}-\dfrac{5}{8}\right)\)
\(=0-\dfrac{8}{8}=-1\)
b: \(-\dfrac{2020}{2021}\cdot\dfrac{9}{11}+\dfrac{-2020}{2021}\cdot\dfrac{2}{11}\)
\(=\dfrac{-2020}{2021}\left(\dfrac{9}{11}+\dfrac{2}{11}\right)\)
\(=-\dfrac{2020}{2021}\)
c: \(\dfrac{2}{-3}=\dfrac{6}{-y}\)
=>\(\dfrac{6}{y}=\dfrac{2}{3}\)
=>\(y=6\cdot\dfrac{3}{2}=9\)