quy đồng
2/6 và 4/5
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1)2/6=14/42 2)5/9=25/45
4/7=24/42 6/5=54/45
3)7/2=28/8 4)4/9=28/63
5/8 =5/8 8/7=72/63
CÁC Ý CÒN LẠI BẠN LÀM NỐT NHÉ
2/6 và 4/7
Mẫu số chung:42
\(\frac{2}{6}=\frac{2\times7}{6\times7}=\frac{14}{42}\);\(\frac{4}{7}=\frac{4\times6}{7\times6}=\frac{24}{42}\)
5/9 và 6/5
Mẫu số chung: 45
\(\frac{5}{9}=\frac{5\times5}{9\times5}=\frac{25}{45}\); \(\frac{6}{5}=\frac{6\times9}{5\times9}=\frac{54}{45}\)
7/2 và 5/8
Mẫu số chung:8
\(\frac{7}{2}=\frac{7\times4}{2\times4}=\frac{28}{8}\);\(\frac{5}{8}\)
4/9 và 8/7
Mẫu số chung: 63
\(\frac{4}{9}=\frac{4\times7}{9\times7}=\frac{28}{63};\frac{8}{7}=\frac{8\times9}{7\times9}=\frac{72}{63}\)
9/4 và 2/6
Mẫu số chung:12
\(\frac{9}{4}=\frac{9\times3}{4\times4}=\frac{27}{12};\frac{2}{6}=\frac{2\times2}{6\times2}=\frac{4}{12}\)
4/3 và 9/4
Mẫu số chung:12
\(\frac{4}{3}=\frac{4\times4}{3\times4}=\frac{16}{12}\);\(\frac{9}{4}=\frac{9\times3}{4\times3}=\frac{27}{12}\)
bài3
1. \(\frac{4}{3}\)= \(\frac{4x4}{3x4}\)=\(\frac{20}{12}\)
\(\frac{3}{4}\)=\(\frac{3x3}{4x3}\)=\(\frac{9}{12}\)
2.\(\frac{5}{4}\)=\(\frac{5x6}{4x6}\)=\(\frac{30}{24}\)
\(\frac{5}{6}\)=\(\frac{5x4}{6x4}\)=\(\frac{20}{24}\)
3.\(\frac{3}{8}\)=\(\frac{3x6}{8x6}\)=\(\frac{18}{48}\)
\(\frac{1}{6}\)=\(\frac{1x6}{6x8}\)=\(\frac{6}{48}\)
4.\(\frac{2}{5}\)=\(\frac{2x7}{5x7}\)=\(\frac{14}{35}\)
\(\frac{4}{7}\)=\(\frac{4x5}{7x5}\)=\(\frac{20}{35}\)
\(\dfrac{7}{18}=\dfrac{7.4}{18.4}=\dfrac{28}{72}\); \(\dfrac{9}{8}=\dfrac{9.9}{8.9}=\dfrac{81}{72}\)
\(\dfrac{2}{3}=\dfrac{2.20}{3.20}=\dfrac{40}{60};\dfrac{3}{4}=\dfrac{3.15}{4.15}=\dfrac{45}{60};\dfrac{6}{5}=\dfrac{6.12}{5.12}=\dfrac{72}{60}\)
\(\dfrac{13}{12}=\dfrac{13.5}{12.5}=\dfrac{65}{60};\dfrac{5}{6}=\dfrac{5.10}{6.10}=\dfrac{50}{60};\dfrac{4}{5}=\dfrac{4.12}{12.5}=\dfrac{48}{60}\)
\(\dfrac{9}{8}=\dfrac{9.8}{8.6}=\dfrac{72}{48};\dfrac{7}{24}=\dfrac{7.2}{24.2}=\dfrac{14}{48};\dfrac{41}{48}\)
a: 2/3=10/15
1/5=3/15
b: 3/4=6/8
5/8=5/8
c: 5/6=15/18
4/9=8/18
\(\dfrac{63}{18}và\dfrac{4}{18}\)
\(\dfrac{18}{21}và\dfrac{17}{21}\)
\(\dfrac{24}{36};\dfrac{9}{36}và\dfrac{20}{36}\)
\(\dfrac{4}{5};\dfrac{5}{6}\) và \(\dfrac{6}{7}\)
Mẫu số chung: 210
Ta có:
\(\dfrac{4}{5}=\dfrac{4\times42}{5\times42}=\dfrac{168}{210}\)
\(\dfrac{5}{6}=\dfrac{5\times35}{6\times35}=\dfrac{175}{210}\)
\(\dfrac{6}{7}=\dfrac{6\times30}{7\times30}=\dfrac{180}{210}\)
\(\frac{10}{x+2};\frac{5}{2x-4};\frac{1}{6-3x}\)
Ta có : \(x+2=x+2\)
\(2x-4=2\left(x-2\right)\)
\(6-3x=3\left(2-x\right)=-3\left(x-2\right)\)
MTC : \(-6\left(x-2\right)\left(x+2\right)\)
\(\frac{10}{x+2}=\frac{10.\left(-6\right)\left(x-2\right)}{-6\left(x-2\right)\left(x+2\right)}=\frac{-60x+120}{-6\left(x-2\right)\left(x+2\right)}\)
\(\frac{5}{2x-4}=\frac{5}{2\left(x-2\right)}=\frac{5.\left(-3\right)\left(x+2\right)}{-6\left(x-2\right)\left(x+2\right)}=\frac{-15x-30x}{-6\left(x-2\right)\left(x+2\right)}\)
\(\frac{1}{6-3x}=\frac{1}{-3\left(x-2\right)}=\frac{2\left(x+2\right)}{-6\left(x-2\right)\left(x+2\right)}=\frac{2x+4}{-6\left(x-2\right)\left(x+2\right)}\)
2/6=2x5/6x5=10/30
4/5=4x6/5x6=24/30
2/6=10/30
4/5=24/30 nha
HT