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`4/7+4`
`=4/7+4/1`
`=4/7+28/7`
`=32/7`
__
`3+6/11`
`=33/11+6/11`
`=39/11`
__
`3-5/7`
`=3/1-5/7`
`=21/7-5/7`
`=16/7`
__
`21/9-2`
`=21/9-18/9`
`=3/9`
`=1/3`
__
`15/24+2`
`=15/24+48/24`
`=63/24`
`=21/16`
__
`63/45-20/25`
`=63/45-4/5`
`=63/45-36/45`
`=27/45`
`=9/15`
__
`3/4-2/8`
`=3/4-1/4`
`=2/4`
__
`6/7-5/8`
`=48/56-35/56`
`=13/56`
__
`37/45-5/9`
`=37/45-25/45`
`=12/45`
`=4/15`
__
`46/39-11/13`
`=46/39-33/39`
`=13/39`
`=1/2`
__
`5/12+3/4+1/3`
`=5/12+9/12+4/12`
`=14/12+4/12`
`=18/12`
`=3/2`
__
`1/2+3/7+11/14`
`=7/14+6/14+11/14`
`=13/14+11/14`
`=24/14`
`=12/7`
__
`7/10-(1/5+1/4)`
`=7/10-(4/20+5/20)`
`=7/10-9/20`
`=14/20-9/20`
`=5/20`
`=1/4`
__
`15/4-2/3-3/4`
`=(15/4-3/4)-2/3`
`=12/4-2/3`
`=3-2/3`
`=9/3-2/3`
`=7/3`
X = ( 1+10 ) * 10 / 2 = 11 * 10 / 2 = 110 / 2 = 55
X= (2+20) * 10 /2 = 110
X= (1+19)*10/2= 100
1+2+3+4+5+6+7+8+9+10= (10+1)X10 : 2 = 55
2+4+6+8+10+12+14+16+18+20 = (20+2)x10 : 2 = 110
1+3+5+7+9+11+13+15+17+19 = (19+1) x 10 : 2 = 100
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10=55
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20=110
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19=100
k mk nha pạn hiền!
10 +1 = 11 có 10 số vậy thì 10 : 2 = 5 thì sẽ bằng 5x11 = 55
2 + 20 = 22 cũng có 10 số lấy 10 : 2 = 5 se bang 22 x5 = 110
1+19 = 20 , 10 : 2 = 5 , 20x5 = 100
a) 1/2x(3/4+2/5)
1/2x23/20
23/40
b) 3/4:(8/9+16/3)
3/4:56/9
27/224
c) 1/5:1/10-1/3
2-1/3
5/3
d) 3/4x(20/9-8/15)
3/4x76/45
19/15
e) 1/7:5/14-3/2
=2/5-3/2
-11/10 ( Chị nghĩ lớp 4 chưa học đến số âm nên em xem lại đề nhé)
g) 3/2x(11/6-5/12)
3/2x17/12
17/8
a)\(\frac{1}{2}x\left(\frac{3}{4}+\frac{2}{5}\right)\)
\(=\frac{1}{2}x\left(\frac{15}{20}+\frac{8}{20}\right)\)
\(=\frac{1}{2}x\frac{23}{20}\)
\(=\frac{23}{40}\)
b)\(\frac{3}{4}:\left(\frac{8}{9}+\frac{16}{3}\right)\)
\(=\frac{3}{4}:\left(\frac{8}{9}+\frac{48}{9}\right)\)
\(=\frac{3}{4}:\frac{56}{9}\)
\(=\frac{3}{4}x\frac{9}{56}\)
\(=\frac{27}{224}\)
c) \(\frac{1}{5}:\frac{1}{10}-\frac{1}{3}\)
\(=\frac{1}{5}x10-\frac{1}{3}\)
\(=2-\frac{1}{3}\)
\(=\frac{6}{3}-\frac{1}{3}=\frac{5}{3}\)
d) \(\frac{3}{4}x\left(\frac{20}{9}-\frac{8}{15}\right)\)
\(=\frac{3}{4}x\left(\frac{100}{45}-\frac{24}{45}\right)\)
\(=\frac{3}{4}x\frac{76}{45}\)
\(=\frac{19}{5}\)
e) \(\frac{1}{7}:\frac{5}{14}-\frac{3}{2}\)
\(=\frac{1}{7}x\frac{14}{5}-\frac{3}{2}\)
\(=\frac{2}{5}-\frac{3}{2}\)
\(=\frac{4}{10}-\frac{15}{10}\)
\(=\frac{-11}{10}\)
g) \(\frac{3}{2}x\left(\frac{11}{6}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\left(\frac{22}{12}-\frac{5}{12}\right)\)
\(=\frac{3}{2}x\frac{17}{12}\)
=\(=\frac{17}{8}\)
a; \(\dfrac{3}{11}\) + \(\dfrac{5}{-9}\) + \(\dfrac{4}{11}\) - \(\dfrac{4}{9}\) + \(\dfrac{3}{17}\) + \(\dfrac{15}{11}\)
= (\(\dfrac{3}{11}\) + \(\dfrac{4}{11}\) + \(\dfrac{15}{11}\)) - (\(\dfrac{5}{9}\) + \(\dfrac{4}{9}\)) + \(\dfrac{3}{17}\)
= 2 - 1 + \(\dfrac{3}{17}\)
= 1 + \(\dfrac{3}{17}\)
= \(\dfrac{20}{17}\)
c; N = \(\dfrac{\dfrac{5}{7}-\dfrac{5}{9}-\dfrac{5}{11}}{\dfrac{15}{7}+\dfrac{15}{9}+\dfrac{15}{11}}\)
Phải là - \(\dfrac{5}{7}\) chỗ tử số mới đúng em nhé!
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: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
(1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20 ) -1-5-9-3=
= ( 1 + 20 ) x 20 : 2 - 1 - 5 - 9 - 3
= 210 - 1 - 5 - 9 - 3
= 192
hok tốt
bn rảnh ghê ha
1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20-1-5-9-3=192
K CHO MIK TRƯỚC ĐI R MIK TRẢ LỜI CHO NHÁK
hay phết tí nữa minh giải cho nhé