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`# \text {DNamNgV}`
`16/21 + 6/7`
`= 16/21 + 18/21`
`= 34/21`
__
`15/22 \times 11/35`
`= (15 \times 11)/(22 \times 35)`
`= (5 \times 3 \times 11)/(2 \times 11 \times 5 \times 7)`
`= (3 \times 1)/(2 \times 7)`
`= 3/14`
___
`8/11 \div 5/22`
`= 8/11 \times 22/5`
`= (8 \times 22)/(11 \times 5)`
`= (8 \times 11 \times 2)/(11 \times 5)`
`= (8 \times 2)/5`
`= 16/5`
___
`9/13 \div 27/39`
`= 9/13 \times 39/27`
`= 9/13 \times 13/9`
`= 1`
a: 4/9+3/7=28/63+27/63=55/63
3/4+7/24=18/24+7/24=25/24
1/3+2/9+4/27=9/27+6/27+4/27=19/27
b: 5/6-3/8=20/24-9/24=11/24
7/15-11/30=14/30-11/30=3/30=1/10
2/3+1/6-7/12
=8/12+2/12-7/12
=3/12=1/4
c: 18/25*15/6=15/25*18/6=3*3/5=9/5
30/49:6/7=30/49*7/6=210/294=5/7
1/2*3/4:6/5=3/8*5/6=15/48=5/16
d: 8*3/5:12/5=24/5*5/12=2
4:9/5:10/3=4*5/9*3/10=2/3
11/9-5/6:15
=11/9-5/6.1/15
=11/9-1/18
=7/6
3/16+(-7/30).15/28
=3/16+(-1/8)
=3/16+(-2/16)
=1/16
\(\dfrac{11}{9}-\dfrac{5}{6}:15=\dfrac{11}{9}-\dfrac{5}{6}\times\dfrac{1}{15}=\dfrac{11}{9}-\dfrac{5}{90}=\dfrac{110}{90}-\dfrac{5}{90}=\dfrac{105}{90}=\dfrac{7}{6}\)
\(\dfrac{3}{16}+\dfrac{-7}{30}\times\dfrac{15}{28}=\dfrac{3}{16}+\left(-\dfrac{1}{8}\right)=\dfrac{3}{16}-\dfrac{1}{8}=\dfrac{3}{16}-\dfrac{2}{16}=\dfrac{1}{16}\)
TL
\(\frac{3}{15}\)-\(\frac{5}{35}\)=\(\frac{1}{5}\)\(-\frac{1}{7}\)=\(\frac{2}{35}\)
\(\frac{18}{27}\)-\(\frac{2}{6}\)=\(\frac{2}{3}\)-\(\frac{1}{3}\)=\(\frac{1}{3}\)
nha bn
HT
\(\dfrac{3}{12}+\dfrac{1}{4}=\dfrac{3:3}{12:3}+\dfrac{1}{4}=\dfrac{1}{4}+\dfrac{1}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)
\(\dfrac{4}{10}+\dfrac{3}{5}=\dfrac{4:2}{10:2}+\dfrac{3}{5}=\dfrac{2}{5}+\dfrac{3}{5}=\dfrac{5}{5}=1\)
\(\dfrac{12}{27}+\dfrac{2}{9}=\dfrac{12:3}{27:3}+\dfrac{2}{9}=\dfrac{4}{9}+\dfrac{2}{9}=\dfrac{6}{9}=\dfrac{2}{3}\)
\(\dfrac{7}{3}+\dfrac{20}{15}=\dfrac{7}{3}+\dfrac{20:5}{15:5}=\dfrac{7}{3}+\dfrac{4}{3}=\dfrac{11}{3}\)
a: \(\dfrac{3}{9}\times\dfrac{5}{4}=\dfrac{5}{4}\times\dfrac{1}{3}=\dfrac{5\times1}{4\times3}=\dfrac{5}{12}\)
b: \(\dfrac{10}{15}\times\dfrac{3}{5}=\dfrac{3}{5}\times\dfrac{2}{3}=\dfrac{3\times2}{5\times3}=\dfrac{2}{5}\)
c: \(\dfrac{5}{8}\times\dfrac{4}{12}=\dfrac{5}{8}\times\dfrac{1}{3}=\dfrac{5}{3\times8}=\dfrac{5}{24}\)
d: \(\dfrac{9}{27}\times\dfrac{3}{21}=\dfrac{1}{7}\times\dfrac{1}{3}=\dfrac{1\times1}{7\times3}=\dfrac{1}{21}\)
\(a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{5\times4\times13}{13\times5\times3}=\dfrac{4}{3}\\ b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\dfrac{3}{7}\times\dfrac{7}{5}+\dfrac{5}{2}\times\dfrac{7}{5}=\dfrac{3}{5}+\dfrac{7}{2}=\dfrac{6}{10}+\dfrac{35}{10}=\dfrac{41}{10}\\ c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}\)
?+3/5=27/15-11/15
?+3/5=16/15
? = 16/15-3/5
? = 16/15-9/15
? = 7/15
Chúc bạn học tốt !!! 10 điểm nha!!!
Gọi số cần tìm là x. Ta có:
x+3/5=27/15-11/15
x+3/5=27-11/15
x+3/5=16/15
x+3.3/5.3=16/15
x+9/15=16/15
x=16/15-9/15
x=16-9/15
x=7/15
Tick cho mình nhé b:) *. là dấu nhân