a) Cách 1:
(`frac{6}{11}` + `frac{5}{11}`) × `frac{3}{7}`
= $1$ × `frac{3}{7}`
= `frac{3}{7}`
Cách 2:
( `frac{6}{11}` + `frac{5}{11}` ) × `frac{3}{7}`
= (`frac{5}{11}` × `frac{3}{7}`) + (`frac{6}{11}` × `frac{3}{7}`)
= `frac{15}{77}` + `frac{18}{77}`
= `frac{33}{77}`
= `frac{3}{7}`
b) Cách 1:
`frac{3}{5}` × `frac{7}{9}` + `frac{3}{5}` × `frac{2}{9}`
= `frac{35}{45 }` + `frac{6}{45}`
= `frac{41}{45}`
Cách 2:
`frac{3}{5}` × `frac{7}{9}` + `frac{3}{5}` × `frac{2}{9}`
= `frac{3}{5 }` × (`frac{7}{9}` + `frac{2}{9}`)
= `frac{3}{5}` × 1
= `frac{3}{5}`
c) Cách 1:
(`frac{6}{7}` - `frac{4}{7}`) : `frac{2}{5}`
=`frac{2}{7}` : `frac{2}{5}`
= `frac{10}{14}` = `frac{5}{7}`
Cách 2:
(`frac{6}{7}` - `frac{4}{7}`) : `frac{2}{5}`
= (`frac{6}{7}` : `frac{2}{5}`) - (`frac{4}{7}` : `frac{2}{5}`)
= `frac{30}{14}` - `frac{20}{14}`
= `frac{10}{14}`
= `frac{5}{7}`
Cách 1:
`frac{8}{15}` : `frac{2}{11}` + `frac{7}{15}` : `frac{2}{11}`
= `frac{88}{30}` + `frac{77}{30}`
= `frac{165}{30}`
= `frac{11}{2}`
Cách 2:
`frac{8}{15}` : `frac{2}{11}` + `frac{7}{15}` : `frac{2}{11}`
= `frac{2}{11}` : (`frac{8}{15}` + `frac{7}{+5}`)
= `frac{2}{11}` : $1$
= `frac{11}{2}`
