bài 5: rút gọn biểu thức sau :( tính nhanh nếu có thể) 1) -5/7.2/11+-5/7.9/11+1 và 5/7 2). 6/7+5/8:5–3/16.(-2)^2 3). 2/3+1/3.( -4/9+5/6) :7/12 Mik

`1) ( – 5 )/7 . 2/11 + ( – 5 )/7 . 9/11 + 1 5/7`

`= ( – 5 )/7 . ( 2/11 + 9/11 ) + 12/7`

`= ( – 5 )/7 . 1 + 12/7`

`= ( – 5 )/7 + 12/7`

`= 1`

`2) 6/7 + 5/8 : 5 – 3/16 . ( – 2 )^2`

`= 6/7 + 5/8 . 1/5 – 3/16 . 4`

`= 6/7 + 1/8 – 3/4`

`= 48/56 + 7/56 – 42/56`

`= 55/56 – 42/56`

`= 13/56`

`3) 2/3 + 1/3 . ( ( – 4 )/9 + 5/6 ) : 7/12`

`= 2/3 + 1/3 . ( ( – 16 )/36 + 30/36 ) : 7/12`

`= 2/3 + 1/3 . 7/18 : 7/12`

`= 2/3 + 1/3 . 7/18 . 12/7`

`= 2/3 + 1/3 . 2/3`

`= 2/3 + 2/6`

`= 4/6 + 2/6`

`= 1`