Mẫu : 5 = 5/1 9=.............
3= ......... 11= .................
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a) \(3\times\dfrac{4}{11}=\dfrac{3\times4}{11}=\dfrac{12}{11}\)
b) \(1\times\dfrac{5}{4}=\dfrac{1\times5}{4}=\dfrac{5}{4}\)
c) \(0\times\dfrac{2}{5}=\dfrac{0\times2}{5}=\dfrac{0}{5}=0\)
a: \(=\dfrac{3\cdot4}{11}=\dfrac{12}{11}\)
b: \(=\dfrac{1\cdot5}{4}=\dfrac{5}{4}\)
c: \(=\dfrac{0\cdot2}{5}=0\)
a: \(5+\dfrac{3}{2}=\dfrac{10}{2}+\dfrac{3}{2}=\dfrac{10+3}{2}=\dfrac{13}{2}\)
\(\dfrac{3}{4}+2=\dfrac{3}{4}+\dfrac{8}{4}=\dfrac{3+8}{4}=\dfrac{11}{4}\)
\(\dfrac{8}{9}+3=\dfrac{8}{9}+\dfrac{27}{9}=\dfrac{8+27}{9}=\dfrac{35}{9}\)
b: \(1-\dfrac{1}{2}=\dfrac{2}{2}-\dfrac{1}{2}=\dfrac{2-1}{2}=\dfrac{1}{2}\)
\(5-\dfrac{7}{3}=\dfrac{15}{3}-\dfrac{7}{3}=\dfrac{15-7}{3}=\dfrac{8}{3}\)
\(\dfrac{11}{2}-3=\dfrac{11}{2}-\dfrac{6}{2}=\dfrac{11-6}{2}=\dfrac{5}{2}\)
`MSC:15`
`2/5=(2xx3)/(5xx3)= 6/15`
`7/15` giữ nguyên
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`MSC : 24`
`3/4=(3xx6)/(4xx6)= 18/24`
`5/6 =(5xx4)/(6xx4)= 20/24`
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`MSC : 99`
`8/9 =(8xx11)/(9xx11)= 88/99`
`8/11=(8xx9)/(11xx9)= 72/99`
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`MSC:30`
`1/2 =(1xx15)/(2xx15)= 15/30`
`2/3=(2xx10)/(3xx10)=20/30`
`3/5=(3xx6)/(5xx6)= 18/30`
\(a,\)\(\dfrac{2}{5};\dfrac{7}{15}\left(MSC:15\right)\)
\(\dfrac{2}{5}=\dfrac{2\times3}{5\times3}=\dfrac{6}{15}\)
\(b,\dfrac{3}{4};\dfrac{5}{6}\left(MSC:12\right)\)
\(\dfrac{3}{4}=\dfrac{3\times3}{4\times3}=\dfrac{9}{12}\)
\(\dfrac{5}{6}=\dfrac{5\times2}{6\times2}=\dfrac{10}{12}\)
\(c,\dfrac{8}{9};\dfrac{8}{11}\left(MSC:99\right)\)
\(\dfrac{8}{9}=\dfrac{8\times11}{9\times11}=\dfrac{88}{99}\)
\(\dfrac{8}{11}=\dfrac{8\times9}{11\times9}=\dfrac{72}{99}\)
\(d,\dfrac{1}{2};\dfrac{2}{3};\dfrac{3}{5}\left(MSC:30\right)\)
\(\dfrac{1}{2}=\dfrac{1\times15}{2\times15}=\dfrac{15}{30}\)
\(\dfrac{2}{3}=\dfrac{2\times10}{3\times10}=\dfrac{20}{30}\)
\(\dfrac{3}{5}=\dfrac{3\times6}{5\times6}=\dfrac{18}{30}\)
a) \(\dfrac{9}{11}\times8=\dfrac{9\times8}{11}=\dfrac{72}{11}\)
b) \(\dfrac{4}{5}\times1=\dfrac{4\times1}{5}=\dfrac{4}{5}\)
c) \(\dfrac{15}{8}\times0=\dfrac{15\times0}{8}=\dfrac{0}{8}=0\)
a: 9/11*8=(9*8)/11=72/11
b: 4/5*1=(4*1)/5=4/5
c: 15/8*0=(15*0)/8=0/8=0
Phương pháp giải:
- Tính giá trị phép nhân.
- Lấy kết quả vừa tìm được trừ đi số còn lại.
Lời giải chi tiết:
a) 5 × 5 − 10 = 25 − 10 = 15
b) 5 × 7 − 5 = 35 − 5 = 30
c) 5 × 9 − 25 = 45 − 25 = 20
d) 5 × 6 − 12 = 30 − 12 = 18
1a)\(\frac{5}{3}\)=\(\frac{5x4}{3x4}\)=\(\frac{20}{12}\); \(\frac{1}{4}\)=\(\frac{1x3}{4x3}\)=\(\frac{3}{12}\)
b)\(\frac{3}{8}\)=\(\frac{3x3}{8x3}\)=\(\frac{9}{24}\); \(\frac{7}{24}\)
c)\(\frac{1}{2}\)=\(\frac{1x15}{2x15}\)=\(\frac{15}{30}\); \(\frac{2}{3}\)=\(\frac{2x10}{3x10}\)=\(\frac{20}{30}\); \(\frac{3}{5}\)=\(\frac{3x6}{5x6}\)=\(\frac{18}{30}\)
2a)\(\frac{11}{8}\)>\(\frac{11}{9}\)
b)\(\frac{4}{9}\)<\(\frac{3}{5}\)
c)\(\frac{6}{5}\)>\(\frac{5}{6}\)
a) \(\dfrac{6}{7}=\dfrac{6\times11}{7\times11}=\dfrac{66}{77}\) ; \(\dfrac{5}{11}=\dfrac{5\times7}{11\times7}=\dfrac{35}{77}\)
b) \(\dfrac{5}{9}=\dfrac{5\times5}{9\times5}=\dfrac{25}{45}\) ; \(\dfrac{9}{5}=\dfrac{9\times9}{5\times9}=\dfrac{81}{45}\)
c) \(\dfrac{3}{8}=\dfrac{3\times3}{8\times3}=\dfrac{9}{24}\) ; \(\dfrac{5}{24}\) giữ nguyên phân số
d) \(\dfrac{6}{5}=\dfrac{6\times6}{5\times6}=\dfrac{36}{30}\) ; \(\dfrac{5}{6}=\dfrac{5\times5}{6\times5}=\dfrac{25}{30}\)
\(#Wendy.Dang\)
a) 6/7 và 5/11
ta có :
6/7=66/77
5/11=35/77
b)5/9 và 9/5
ta có
5/9=25/45
9/5=81/45
C)3/8 và 5/24
ta có :
3/8=9/24
5/24
D)6/5 và 5/6
ta có
6/5=36/30
5/6=25/30
Bài làm:
\(\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\right).y=\frac{2}{3}\)
\(\Leftrightarrow\left(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\right).y=\frac{4}{3}\)
\(\Leftrightarrow\left(\frac{3-1}{1.3}+\frac{5-3}{3.5}+\frac{7-5}{5.7}+\frac{9-7}{7.9}+\frac{11-9}{9.11}\right).y=\frac{4}{3}\)
\(\Leftrightarrow\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\right).y=\frac{4}{3}\)
\(\Leftrightarrow\left(1-\frac{1}{11}\right).y=\frac{4}{3}\)
\(\Leftrightarrow\frac{10}{11}.y=\frac{4}{3}\)
\(\Leftrightarrow y=\frac{4}{3}:\frac{10}{11}=\frac{4}{3}.\frac{11}{10}=\frac{22}{15}\)
Chú ý dấu \(\left(.\right)\)là dấu \(\left(\times\right)\)
Vậy \(y=\frac{22}{15}\)
\(\left(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+\frac{1}{7.9}+\frac{1}{9.11}\right).y=\frac{2}{3}\)
\(\Leftrightarrow\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\right).y=\frac{2}{3}\)
\(\Leftrightarrow\frac{1}{2}.\left(1-\frac{1}{11}\right).y=\frac{2}{3}\)
\(\Leftrightarrow\frac{1}{2}.\frac{10}{11}.y=\frac{2}{3}\)
\(\Leftrightarrow\frac{5}{11}.y=\frac{2}{3}\)
\(\Rightarrow y=\frac{2}{3}:\frac{5}{11}=\frac{22}{15}\)
LƯU Ý:các dấu chấm(.) là dấu nhân ^^.
\(3=\dfrac{3}{1};9=\dfrac{9}{1};11=\dfrac{11}{1}\)
Chúc bạn học tốt
9 = \(\dfrac{9}{1}\)
3 = \(\dfrac{3}{1}\) 11 = \(\dfrac{11}{1}\)