Đáp án: `a ) 0`
`b ) -101/14`
`c ) -1/3`
`d ) 21/16 `
Giải thích các bước giải:
`a) 13``4/5 : 207/2020 - 12``2/5 : 186/2020 `
`= 69/5 . 2020/207 - 62/5 . 2020/186`
`= 1/5 . 69 . 2020 . 1/207 - 62 . 1/5 . 2020 . 1/186 `
`= 1/5 . 2020 . [ 69. 1/207 - 62 . 1/186 ] `
`= 1/5 . 2020 . [ 1/3 - 1/3 ] `
`= 1/5 . 2020 . 0 = 0 `
`b) 7``3/4 - 15``3/7 + 13/28`
`= 31/4 - 108/7 + 13/28`
`= 217/28 - 432/28 + 13/28`
`= -101/14`
`c) 4/24 . 10/19 + 4/24 . 9/19 - 6/12 `
`= 4/24 . [ 10/19 + 9/19 ] - 6/12`
`= 2/12 . 1 - 6/12 `
`= -4/12 = -1/3`
`d) ( -3/4 )^2 - | -1/4 | + 2/7 + 5/7 `
`= 9/16 - 1/4 + ( 2/7 + 5/7 ) `
`= ( 9/16 - 4/16 ) + 1 `
`= 5/16 + 1 = 5/16 + 16/16 = 21/16 `