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a. \(\left(\dfrac{-2}{7}+\dfrac{4}{7}\right)+\dfrac{1}{7}=\dfrac{2}{7}+\dfrac{1}{7}=\dfrac{3}{7}\)
b. \(\left(\dfrac{-8}{19}+\dfrac{27}{19}\right)+\left(\dfrac{-4}{21}+\dfrac{-17}{21}\right)+\dfrac{-12}{16}=\dfrac{19}{19}+\dfrac{-21}{21}+\dfrac{-12}{16}\)
\(=1+\left(-1\right)+\dfrac{-12}{16}=\dfrac{-12}{16}\)
c. \(\dfrac{-3}{7}+\dfrac{-11}{13}+\dfrac{-2}{13}+\dfrac{3}{7}+1=\left(\dfrac{-3}{7}+\dfrac{3}{7}\right)+\left(\dfrac{-11}{13}+\dfrac{-2}{13}\right)+1=0-1+1=0\)
-2/7 + 2/7 : 3/5
= -2/7 + 2/7. 3/5
= -2/7 + 35/6
= -12/42 + 245/42
= -233/42
−819+−421−1721+271919−8+21−4−2117+1927
= (-4/21 - 17/21) + (-8/19 + 27/19)
= - 13/21 + -19/19
= (-13/21)+ (-1)
= (-13/21) + (-1/1)
= (-13/21) + (-13/21)
= - 26/21
65.313−65.161356.133−56.1316
=6/5. (3/13 - 16/13)
= 6/5. (-13/13)
=6/5. (-1)
=6/5. (-1/1)
=6/5. (-6/5)
=(-36/25)
a. (−27+47)+17=27+17=37(7−2+74)+71=72+71=73
b. (−819+2719)+(−421+−1721)+−1216=1919+−2121+−1216(19−8+1927)+(21−4+21−17)+16−12=1919+21−21+16−12
=1+(−1)+−1216=−1216=1+(−1)+16−12=16−12
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a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
Đúng(0)
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
Đúng(0)
ủa alo
a)
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
Đúng(0)
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=21
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+21−
Đúng(0)
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
Đúng(0)
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+
Đúng(0)
(7−2+74)+71=72+71=73
b. (−819+2719)+(−421+−1721)+−1216=1919+−2121+−1216(19−8+1927)+(21−4+21−17)+16−12=1919+21−21+16−12
=1+(−1)+−1216=−1216=1+(−1)+16−12=16−12
c. <...
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+21<...
a) −27+27:357−2+72:53
=−27+27.53=7−2+72.35
=−27+1021=7−2+2110
=−621+1021=21−6+2110
=421=214
b)−819+−421−1721+271919−8+21−4−2117+1927
=−819+−421+−1721+2719=19−8+21<...
7477474
a)4/21
b)0
c)114/65
a, -2/7 + 3/7 ÷ 3/5
= -2/7 + 2/7 × 3/5
= -2/7 + 10/21
= -6/7 + 10/21 = 4/21
b, -8/19 + -4/21-17/21 + 27/19
= (-8/19 + 27/19) + (-4/21- 17/21)
= 1 + (-1)
= 0
c, -6/21 + 3/13 - 6/5 × 16/13
= 6/5 × (3/13 - 6/13)
= 6/5 × -3/13
= -18/65
-2/7+2/7:3/5
= 0 : 3/5
= 0
-8/19+(-4/21)-17/21+27/19
= [(-8/19)+27/19]-[(-4/21)+17/21]
= 1 - 1
= 0
=6/5*3/13-6/5*16/13
=6/5*(16/13-3/13)
=6/5*1
=6/5
-8/19+ -4/21 -17/21 +27/19
=(-8/19+27/19)+(-4/21-17/21)
=(-8/19+27/19)+(4/21+27/21)
=1+1=2
6/5.3/13-6/5.16/13
=6/5.(16/13-3/13)
=6/5.1
=6/5
Câu trả lời:
A,-2/7+2/7÷3/5
=2/7÷3/5=2/7×3/5
=10/21=-2/7+10/21
=-6/21+10/21
=4/21
B,-8/19+-4/21-17/21+27/19
=(-8/19+27/19)-(-4/21-17/21)
=19/19 =1
=-21/21=-1
=1-(-1)=0
C,6/5×3/13-6/5×16/13
=6/5×(3/13-16/13)
=3/13-16/13=-13/13=-1
=6/5×(-1)
=-6/5
Ydyyr
a) 1: 3/5
b)-2/21
G
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bài 3 thực hiện phép tính
a\(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
b\(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
c\(\left(\dfrac{13}{5}+\dfrac{7}{16}\right)+\left(\dfrac{-15}{16}+\dfrac{6}{15}\right)\) d \(\left(6-2\dfrac{4}{5}\right).3\dfrac{1}{8}-1\dfrac{3}{5}:\dfrac{1}{4}\)
a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=-1+1=0\)
b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)
=1-1+1=1
Thực hiện phép tính (tính hợp lí nếu có thể):
a) \(\dfrac{5}{3}.\dfrac{7}{25}+\dfrac{5}{3}.\dfrac{21}{25}-\dfrac{5}{3}.\dfrac{7}{25}\) b) 250% + \(19\dfrac{3}{11}.\dfrac{7}{26}-6\dfrac{3}{11}.\dfrac{7}{26}\)
\(\dfrac{5}{3}\cdot\dfrac{7}{25}+\dfrac{5}{3}\cdot\dfrac{21}{25}-\dfrac{5}{3}\cdot\dfrac{7}{25}\)
\(=\dfrac{5}{3}\cdot\left(\dfrac{7.}{25}+\dfrac{21}{25}-\dfrac{7}{25}\right)\)
\(=\dfrac{5}{3}\cdot\dfrac{21}{25}=\dfrac{7}{5}\)
b) \(250\%+19\dfrac{3}{11}\cdot\dfrac{7}{26}-6\dfrac{3}{11}\cdot\dfrac{7}{26}\)
\(=\dfrac{5}{2}+\dfrac{212}{11}\cdot\dfrac{7}{26}-\dfrac{69}{11}\cdot\dfrac{7}{26}\)
\(=\dfrac{7}{26}\cdot\left(\dfrac{212}{11}-\dfrac{69}{11}\right)+\dfrac{5}{2}\)
\(=\dfrac{7}{26}\cdot13+\dfrac{5}{2}\)
\(=\dfrac{7}{2}+\dfrac{5}{2}\)
\(=\dfrac{12}{2}=6\)
Thực hiện phép tính (tính hợp lý nếu có thể):
a) \(\dfrac{5}{9}.\dfrac{7}{13}+\dfrac{5}{9}.\dfrac{8}{13}-\dfrac{5}{13}.\dfrac{2}{9}\) b) \(12\dfrac{5}{14}-\left(3\dfrac{5}{7}+5\dfrac{5}{14}\right)\)
c)\(\dfrac{-2}{5}+\dfrac{7}{11}+\dfrac{-11}{10}+\dfrac{7}{-11}\) d) \(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)
b: =12+5/14-3-5/7-5-5/14
=4-5/7
=28/7-5/7=23/7
c: =(-2/5-11/10)+(7/11-7/11)
=-4/10-11/10=-15/10=-3/2
\(a,\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{5}{13}\cdot\dfrac{2}{9}\)
\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{2}{13}\cdot\dfrac{5}{9}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{8}{13}-\dfrac{2}{13}\right)\)
\(=\dfrac{5}{9}\cdot\dfrac{14}{13}\)
\(=\dfrac{70}{117}\)
\(d,\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)
\(=\left(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}\right)+\dfrac{-2}{5}\)
\(=0+\dfrac{-2}{5}\)
\(=\dfrac{-2}{5}\)
Tính hợp lý nếu có thể:
a) \(\dfrac{2}{9}+\dfrac{-3}{10}+\dfrac{-7}{10}\)
b) \(\dfrac{-11}{6}+\dfrac{2}{5}+\dfrac{-1}{6}\)
c) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111}\)
d) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}\)
a, \(=\dfrac{2}{9}-\dfrac{10}{10}=\dfrac{2}{9}-1=-\dfrac{7}{9}\)
b, \(=-\dfrac{12}{6}+\dfrac{2}{5}=-2+\dfrac{2}{5}=-\dfrac{8}{5}\)
c, \(=\dfrac{27}{13}-1=\dfrac{14}{13}\)
d, \(=\dfrac{12}{11}+\dfrac{7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+1=\dfrac{23}{11}\)
a) \(\dfrac{2}{9}+\dfrac{-3}{10}+\dfrac{-7}{10}\)
\(=\dfrac{2}{9}+\dfrac{-10}{10}=\dfrac{2}{9}-1=-\dfrac{7}{9}\)
b) \(\dfrac{-11}{6}+\dfrac{2}{5}+\dfrac{-1}{6}\)
\(=-2+\dfrac{2}{5}=-\dfrac{8}{5}\)
Thực hiện phép tính (tính nhanh nếu có thể)
a) -19+7+9+19
b) \(11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)
c) \(\dfrac{2}{7}.5\dfrac{1}{4}-\dfrac{2}{7}.3\dfrac{1}{4}\)
a: =9+7=16
b: =11+3/13-2-4/7-5-3/13
=4-4/7
=28/7-4/7=24/7
c: =2/7(5+1/4-3-1/4)=2/7x2=4/7
Thực hiện phép tính( tính nhanh nếu có thể)
a, \(\left(-\dfrac{1}{2}\right)^2.\dfrac{7}{4}:\left(\dfrac{5}{8}-1\dfrac{3}{16}\right)\)
b, \(17\dfrac{6}{11}.\dfrac{4}{27}-8\dfrac{6}{11}:\dfrac{27}{4}+350\%\)
Thực hiện phép tính (tính hợp lý nếu có thể): \(\dfrac{-5}{6}.\dfrac{4}{19}+\dfrac{-7}{12}.\dfrac{4}{19}-\dfrac{40}{57}\)
\(=\dfrac{4}{19}\left(\dfrac{-5}{6}-\dfrac{7}{12}-\dfrac{10}{3}\right)\)
\(=\dfrac{4}{19}\cdot\left(\dfrac{-10-7-40}{12}\right)=\dfrac{4}{19}\cdot\dfrac{-57}{12}=-\dfrac{3}{3}=-1\)
=\(\dfrac{4}{19}.\left(-\dfrac{5}{6}+-\dfrac{7}{12}\right)-\dfrac{40}{57}\)
=\(-\dfrac{4}{19}-\dfrac{40}{57}\)
=\(-\dfrac{52}{57}\)
Thực hiện phép tính ( tính hợ lí nếu được)
a, \(\dfrac{3}{4}+\dfrac{9}{5}:\dfrac{3}{2}-1\) b, \(\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{4}{13}.\dfrac{6}{7}\)
a: \(=\dfrac{3}{4}+\dfrac{9}{5}\cdot\dfrac{2}{3}-1=\dfrac{3}{4}+\dfrac{6}{5}-1=\dfrac{19}{20}\)
b: \(=\dfrac{6}{7}\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)=\dfrac{6}{7}\cdot\dfrac{13}{13}=\dfrac{6}{7}\)
Thực hiện phép tính ( tính hợ lí nếu được)
a, \(\dfrac{3}{4}+\dfrac{9}{5}:\dfrac{3}{2}-1\) b, \(\dfrac{6}{7}.\dfrac{8}{13}+\dfrac{6}{13}.\dfrac{9}{7}-\dfrac{4}{13}.\dfrac{6}{7}\)
= \(\dfrac{3}{4}+\dfrac{6}{5}-1\) = \(\dfrac{6}{7}.\left(\dfrac{8}{13}+\dfrac{9}{13}-\dfrac{4}{13}\right)\)
= \(\dfrac{15}{20}+\dfrac{24}{20}-\dfrac{20}{20}\) = \(\dfrac{6}{7}.\left(\dfrac{17}{13}-\dfrac{4}{13}\right)\)
= \(\dfrac{39}{20}-\dfrac{20}{20}\) = \(\dfrac{6}{7}.1\)
= \(\dfrac{19}{20}\) = \(\dfrac{6}{7}\)
Thực hiện phép tính (3 điểm).
a) $\dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}$ ;
b) $\dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}$ ;
c) $\dfrac{3}{5} \cdot \dfrac{8}{9}-\dfrac{7}{9} \cdot \dfrac{3}{5}+\dfrac{3}{5} \cdot \dfrac{26}{9}$.
Bài 1:
\(a,=\frac{2}{3}-\frac{16}{3}=\frac{-14}{3}\)
\(b,=\left(\frac{3}{7}+\frac{4}{7}\right)+\left(-\frac{6}{19}+\frac{-13}{19}\right)=1-1=0\)
\(c,=\frac{3}{5}.\left(\frac{8}{9}-\frac{7}{9}+\frac{26}{9}\right)=\frac{3}{5}.3=\frac{9}{5}\)
a,\(\dfrac{1}{2}\).\(\dfrac{4}{3}\)-\(\dfrac{20}{3}\).\(\dfrac{4}{5}\)=\(\dfrac{2}{3}\)-\(\dfrac{16}{3}\)=-\(\dfrac{14}{3}\)
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