Bài 1 : tính nhanh a. 5/7 – 4/9 + 2/7 – 15/19 – 1999/2006 b. 3/8 – 7/9 + 10/16 – 2/9 + 15/27 11/09/2021 Bởi Faith Bài 1 : tính nhanh a. 5/7 – 4/9 + 2/7 – 15/19 – 1999/2006 b. 3/8 – 7/9 + 10/16 – 2/9 + 15/27
Đáp án: Giải thích các bước giải: ` a) 5/7 – 4/9 + 2/7 – 15/19 – 1999/2006 ` ` = ( 5/7 + 2/7 ) – (4/19 – 15/19) – 1999/2006 ` ` = 1 + (-1) – 1999/2006 ` ` = – 1999/2006 ` 3/8 – 7/9 + 10/16 – 2/9 + 15/27 ` ` = ( 3/8 + 10/16 ) + ( -7/9 -2/9 ) + 15/27 ` ` = 1 -1 + 15/27 ` ` = 15/27` Bình luận
$#Dino$ `a) 5/7-4/19+2/7-15/19-1999/2006` `=(5/7+2/7)+(-4/19-15/19)-1999/2006` `=1-1-199/2006` `=-1999/2006` …………………. `b) 3/8-7/9+10/16-2/9+15/27` `=(6/16+10/16)+(-7/9-2/9)+15/27` `=1-1+15/27` `=15/27` Bình luận
Đáp án:
Giải thích các bước giải:
` a) 5/7 – 4/9 + 2/7 – 15/19 – 1999/2006 `
` = ( 5/7 + 2/7 ) – (4/19 – 15/19) – 1999/2006 `
` = 1 + (-1) – 1999/2006 `
` = – 1999/2006
` 3/8 – 7/9 + 10/16 – 2/9 + 15/27 `
` = ( 3/8 + 10/16 ) + ( -7/9 -2/9 ) + 15/27 `
` = 1 -1 + 15/27 `
` = 15/27`
$#Dino$
`a) 5/7-4/19+2/7-15/19-1999/2006`
`=(5/7+2/7)+(-4/19-15/19)-1999/2006`
`=1-1-199/2006`
`=-1999/2006`
………………….
`b) 3/8-7/9+10/16-2/9+15/27`
`=(6/16+10/16)+(-7/9-2/9)+15/27`
`=1-1+15/27`
`=15/27`