Tính:
a) 2/9 + 5/6 × 4/7
b) 21/25 + 4/5 :8/6
c) 17/24 - 1/3 + 3/4
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a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
2:
a: \(2^2\cdot3-4=4\cdot3-4=12-4=8\)
b: \(16-2^3\cdot2=16-2^4=16-16=0\)
c: \(4^2-4\cdot2=16-8=8\)
d: \(3^3-2\cdot3^2=27-2\cdot9=27-18=9\)
e: \(7^2-9\cdot2^2=49-9\cdot4=49-36=13\)
f: \(2^2\cdot3+4^2=4\cdot3+16=12+16=28\)
Bài 1:
a: \(13+21\cdot5-\left(198:11-8\right)\)
\(=13+105-18+8\)
=21+87
=108
b: \(272:16-5+4\cdot\left(30-5-255:17\right)\)
\(=17-5+4\cdot\left(30-5-15\right)\)
\(=12+4\cdot10=12+40=52\)
c: \(15\cdot24-14\cdot5\cdot\left(145:5-27\right)\)
\(=360-70\left(29-27\right)\)
=360-140
=220
d: \(18\cdot3-18\cdot2+3\cdot\left(\dfrac{51}{17}\right)\)
\(=18\left(3-2\right)+3\cdot3\)
=18+9
=27
e: \(64+115+36-25\cdot8\cdot6\cdot2^2\cdot3+4^2\)
\(=100+115-200\cdot6\cdot4\cdot3+16\)
\(=231-14400=-14169\)
f: \(15\cdot8-\left(17-30+83\right)-144:6\)
\(=120-24-\left(100-30\right)\)
=96-70
=26
2. Tính (+5) + ( +4) = 9
3.Tính (- 9) + ( - 1) = -10
4.Tính : 28 + (-15) = 13
5.Tính (-15) + 12 = - 3
6.Tính (-25) + 25 = 0
7.Tính : 13 - 17 = - 4
8.Tính : (-78) - 9 = - 87
9.Tính : ( -24) - ( - 16) = - 8
10.Tính : 17 - (-3) = 20
11.Tính nhanh : (-21) - ( 48 + 52 - 21) = -100
2, (+5)+(+4)=+9 hoạc 9 cũng được
3, (-9)+(-1)=-10
4, 28+(-15)=13
5, (-15)+12=-3
6, (-25)+25=0
7, 13-17=4
8, (-78)-9=-87
9, (-24)-(-16)=-40
10, 17-(-3)=20
11, (-21+21)-(48-52)=-4
a: =2/3+2/7=14/21+6/21=20/21
b: =17/18-33/18=-16/18=-8/9
c: =7/12-3/14=49/84-18/84=31/84
d: =-1/4-1/8=-3/8
a: \(\dfrac{18}{24}+\dfrac{35}{-21}-\dfrac{1}{2}\)
\(=\dfrac{3}{4}-\dfrac{5}{3}-\dfrac{1}{2}\)
\(=\dfrac{9-20-6}{12}=\dfrac{-17}{12}\)
b: \(\dfrac{-2}{3}-\dfrac{3}{-4}+\dfrac{5}{-6}\)
\(=-\dfrac{2}{3}+\dfrac{3}{4}-\dfrac{5}{6}\)
\(=\dfrac{-8+9-10}{12}=\dfrac{-9}{12}=\dfrac{-3}{4}\)
c: \(\left(\dfrac{3}{4}+\dfrac{-7}{2}\right)\cdot\left(\dfrac{10}{11}+\dfrac{2}{22}\right)\)
\(=\left(\dfrac{3}{4}-\dfrac{14}{4}\right)\cdot\left(\dfrac{10}{11}+\dfrac{1}{11}\right)\)
\(=-\dfrac{11}{4}\cdot1=-\dfrac{11}{4}\)
d: \(\left(\dfrac{7}{3}-\dfrac{-7}{2}\right):\left(-\dfrac{25}{6}\cdot\dfrac{1}{5}\right)\)
\(=\left(\dfrac{7}{3}+\dfrac{7}{2}\right):\dfrac{-5}{6}\)
\(=\dfrac{35}{6}\cdot\dfrac{6}{-5}=\dfrac{35}{-5}=-7\)
a) \(\dfrac{18}{24}+\dfrac{35}{-21}-\dfrac{1}{2}\)
\(=\dfrac{3}{4}-\dfrac{5}{3}-\dfrac{1}{2}\)
\(=\dfrac{9}{12}-\dfrac{20}{12}-\dfrac{6}{12}\)
\(=\dfrac{-17}{12}\)
b) \(\dfrac{-2}{3}-\dfrac{3}{-4}+\dfrac{5}{-6}\)
\(=\dfrac{-8}{12}+\dfrac{9}{12}-\dfrac{10}{12}\)
\(=\dfrac{-9}{12}\)
\(=\dfrac{-3}{4}\)
c) \(\left(\dfrac{3}{4}+\dfrac{-7}{2}\right).\left(\dfrac{10}{11}+\dfrac{2}{22}\right)\)
\(=\dfrac{-11}{4}.1\)
\(=\dfrac{-11}{4}\)
d) \(\left(\dfrac{7}{3}-\dfrac{-7}{2}\right):\left(-\dfrac{25}{6}.\dfrac{1}{5}\right)\)
\(=\dfrac{35}{6}:\dfrac{-5}{6}\)
\(=-7\)
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 +16 +17 +18 + 19 + 20 + 21 + 22 + 23 + 24 + 25=325
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 + 13 + 14 + 15 +16 +17 +18 + 19 + 20 + 21 + 22 + 23 + 24 + 25 = 325
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}\)
\(=\frac{2}{9}+\frac{10}{21}\)
\(=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}:\frac{8}{6}\)
\(=\frac{21}{25}+\frac{3}{5}\)
\(=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}\)
\(=\frac{3}{8}+\frac{3}{4}\)
\(=\frac{9}{8}\)
a) \(\frac{2}{9}+\frac{5}{6}\times\frac{4}{7}=\frac{2}{9}+\frac{10}{21}=\frac{14}{63}+\frac{30}{63}=\frac{44}{63}\)
b) \(\frac{21}{25}+\frac{4}{5}\div\frac{8}{6}=\frac{21}{25}+\frac{4}{5}\times\frac{6}{8}=\frac{21}{25}+\frac{3}{5}=\frac{21}{25}+\frac{15}{25}=\frac{36}{25}\)
c) \(\frac{17}{24}-\frac{1}{3}+\frac{3}{4}=\frac{17}{24}-\frac{8}{24}+\frac{18}{24}=\frac{27}{24}=\frac{9}{8}\)