Giúp e với anh chị ạ

a) `2/5` , `13/15` , `19/45`

Ta có:

`5`=`5`

`15`=`5`×`3`

`45`=`3^2`×`5`

BCNN(`5`,`15`,`45`)=`45`

`2/5`=`(2×9)/(5×9)`=`18/45`

`13/15`=`(13×3)/(15×3)`=`39/45`

`19/45` giữ nguyên

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b) `1/2`,`3/8`,`5/4`,`7/16`

Ta có:

BCNN(`2`,`8`,`4`,`16`)=`16`

`1/2`=`(1×8)/(2×8)`=`8/16`

`3/8`=`(3×2)/(8×2)`=`6/16`

`5/4`=`(5×4)/(4×4)`=`20/16`

`7/16` giữ nguyên