a: 3/7=15/35
2/5=14/35
b: 3/8=9/24
7/12=14/24
c: 11/12=44/48
7/48=7/48
d: 1/2=6/12
2/3=8/12
3/4=9/12
e: 1/3=15/45
2/15=6/45
4/45=4/45
\(a.\dfrac{3}{7}=\dfrac{15}{35};\dfrac{2}{5}=\dfrac{14}{35}.\\ b.\dfrac{3}{8}=\dfrac{9}{24};\dfrac{7}{12}=\dfrac{14}{24}.\\ c.\dfrac{11}{12}=\dfrac{44}{48};\dfrac{7}{48}.\)
\(d.\dfrac{1}{2}=\dfrac{6}{12};\dfrac{2}{3}=\dfrac{8}{12};\dfrac{3}{4}=\dfrac{9}{12}.\\ e.\dfrac{1}{3}=\dfrac{15}{45};\dfrac{2}{15}=\dfrac{6}{45};\dfrac{4}{45}.\)
\(a,\dfrac{3}{7}và\dfrac{2}{5}\)
\(\dfrac{3}{7}=\dfrac{3\times5}{7\times5}=\dfrac{15}{35}\)\(;\dfrac{2}{5}=\dfrac{2\times7}{5\times7}=\dfrac{14}{35}\)
\(b,\dfrac{3}{8}và\dfrac{7}{12}\)
\(\dfrac{3}{8}=\dfrac{3\times3}{8\times3}=\dfrac{9}{24};\dfrac{7}{12}=\dfrac{7\times2}{12\times2}=\dfrac{14}{24}\)
\(c,\dfrac{11}{12}và\dfrac{7}{48}\)
\(\dfrac{11}{12}=\dfrac{11\times4}{12\times4}=\dfrac{44}{48};\dfrac{7}{48}\)
\(d,\dfrac{1}{2};\dfrac{2}{3}và\dfrac{3}{4}\)
\(\dfrac{1}{2}=\dfrac{1\times6}{2\times6}=\dfrac{6}{12};\dfrac{2}{3}=\dfrac{2\times4}{3\times4}=\dfrac{8}{12};\dfrac{3}{4}=\dfrac{3\times3}{4\times3}=\dfrac{9}{12}\)
\(e,\dfrac{1}{3};\dfrac{2}{15}và\dfrac{4}{45}\)
\(\dfrac{1}{3}=\dfrac{1\times15}{3\times15}=\dfrac{15}{45};\dfrac{2}{15}=\dfrac{2\times3}{15\times3}=\dfrac{6}{45};\dfrac{4}{45}\)
Bài 3 :
a) \(\dfrac{3}{7}\)=\(\dfrac{3x5}{7x5}\)=\(\dfrac{15}{35}\)
\(\dfrac{2}{5}\)=\(\dfrac{2x7}{5x7}\)=\(\dfrac{14}{35}\) ( MSC là 35 )
b) \(\dfrac{3}{8}\)=\(\dfrac{3x12}{8x12}\)=\(\dfrac{36}{96}\)
\(\dfrac{7}{12}\)=\(\dfrac{7x8}{12x8}\)=\(\dfrac{56}{96}\) ( MSC là 96 )
c) \(\dfrac{11}{12}\)=\(\dfrac{11x4}{12x4}\)=\(\dfrac{44}{48}\)
\(\dfrac{7}{48}\) giữ nguyên ( MSC là 48 )
d) \(\dfrac{1}{2}\)=\(\dfrac{1x3x4}{2x3x4}\)=\(\dfrac{12}{24}\)
\(\dfrac{2}{3}\)=\(\dfrac{2x2x4}{3x2x4}\)=\(\dfrac{16}{24}\)
\(\dfrac{3}{4}\)=\(\dfrac{3x2x3}{4x2x3}\)= \(\dfrac{18}{24}\) ( MSC là 24 )
e) \(\dfrac{1}{3}\)=\(\dfrac{1x15x45}{3x15x45}\)=\(\dfrac{675}{2025}\)
\(\dfrac{2}{15}\)=\(\dfrac{2x3x45}{15x3x45}\)=\(\dfrac{270}{2025}\)
\(\dfrac{4}{45}\)=\(\dfrac{4x15x3}{45x15x3}\)=\(\dfrac{180}{2025}\) ( MSC là 2025 )
