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3/2-5/6+7/12-9/20+11/30-13/42+15/56-17/72
=1.5-0.8(3)+0.58(3)-0.3(6)-0.3(095238)+0.267(857142)-0236(1)
=0.(8)
tính nhanh nha bn thế là chưa tinh nhanh đâu
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
a) 5/17 * 8/-7+8/17*-7/3+-7/3*4/17
-40/119 + 12/17 × -7/3
-40/119 + -28/17 =-236/119
b) -10/13 + 5/17 - 3/13 + 12/17 - 11/20
(5/17+12/17)-(10/13+3/13)-11/20
-11/20
a) \(\dfrac{3}{8}+\dfrac{7}{12}+\dfrac{10}{16}+\dfrac{10}{24}\)
\(=\dfrac{3}{8}+\dfrac{7}{12}+\dfrac{5}{8}+\dfrac{5}{12}\)
\(=\left(\dfrac{3}{8}+\dfrac{5}{8}\right)+\left(\dfrac{7}{12}+\dfrac{5}{12}\right)\)
\(=1+1\)
\(=2\)
b) \(\dfrac{4}{6}+\dfrac{7}{13}+\dfrac{17}{9}+\dfrac{19}{13}+\dfrac{1}{9}+\dfrac{14}{6}\)
\(=\dfrac{2}{3}+\dfrac{7}{13}+\dfrac{17}{9}+\dfrac{19}{13}+\dfrac{1}{9}+\dfrac{7}{3}\)
\(=\left(\dfrac{2}{3}+\dfrac{7}{3}\right)+\left(\dfrac{7}{13}+\dfrac{19}{13}\right)+\left(\dfrac{17}{9}+\dfrac{1}{9}\right)\)
\(=3+2+2\)
\(=7\)
c) \(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\)
\(=\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}\)
\(=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}\)
\(=1-\dfrac{1}{7}\)
\(=\dfrac{6}{7}\)
a, (-17) + 21 + 79 + 17
= (-17 + 17) + (21 + 79)
= 0 + 100
= 100
b, 40 + 22 + (-16) + (-44)
= 40 + {(-16) + (-44} + 22
= 40 - 60 + 22
= - 20 + 22
= 2
c, (-12) + (-47) + (-28) + 47
= - (12 + 28) + (-47 + 47)
= - 40 + 0
= - 40
d, (- 5) + (-3) + 35 + (-17)
= (-5 + 35) - (3 + 17)
= 30 - 20
= 10
a) 35- {12 - [(-14)+(-2)] }
=35 - [12-(-14-2)]
=35-[12-16]
=35-(-4)
=35+4
=39
b) 49 - (- 54) - 23
=49 + 54 - 23
= 80
c) |31 - 17 | - |13 - 52|
= |14| - | -39|
=14-39
= -25
d) -|-5|+ (-19) + 18 +|11-4| - 57
=-5 - 19 + 18 + 7 - 57
= -5-1-50
=-56
e) 126 + (-20) + |124| - (- 320) - |- 150|
= 126 - 20 + 124 + 320 - 150
= 400
g) (- 17) + 5 +8 +17 + (-3)
=(-17+17)+(5+8-3)=10
h) [( -15) + ( - 21 )] - ( 25 -15 - 35- 21)
=-15-21-25+15+35+21
=(-15+15)+(21-21)+(35+15-25)
=25
=-4 - 46
= -50 Tick cho mik nha
a) \(30+\left(-30\right)+7\)
\(=30-30+7\)
\(=0+7\)
\(=7\)
b) \(12+\left(-31\right)\)
\(=12-31\)
\(=-31+12\)
\(=-\left(31-12\right)\)
\(=-19\)
c) \(\left(-40\right)+\left(-20\right)+\left(-40\right)\)
\(=-40-20-40\)
\(=-\left(40+20\right)-40\)
\(=-60-40\)
\(=-\left(60+40\right)\)
\(=-100\)
d) \(13+\left|-13\right|\)
\(=13+13\)
\(=26\)
e) \(\left|-13\right|+\left|-12\right|+\left|-17\right|\)
\(=13+12+17\)
\(=25+17\)
\(=42\)
f) \(-17+\left|-17\right|+12\)
\(=-17+17+12\)
\(=-\left(17-17\right)+12\)
\(=-0+12\)
\(=-\left(0-12\right)\)
\(=-\left(-12\right)\)
\(=12\)
cảm ơn bạn