Đáp án:
Giải thích các bước giải:
`a) 3/10 - 7/5 + 1/2 `
`= -11/10 + 1/2 `
`=-3/5 `
`b) ( 1/2 - 1/3 - 1/6 ) . ( 2013/2014+ 2014/2015 ) `
`= 0 . 1,9 `
`= 0`
`c) (1/2)^2 - 45/54 + 1/3 `
`=1/4 - 45/54 + 1/3 `
`=-7/12 + 1/3 `
`=-1/4 `
`d) 0,75 - 43/80 : (-4/5 + 2,5 . 3/4 ) `
`=3/4 - 43/80 : ( -4/5 + 5/2 . 3/4 ) `
`= 3/4 - 43/80 : ( -4/5 + 15/8 ) `
`= 3/4 - 43/80 : 43/40 `
`= 3/4 - 1/2 `
`=1/4 `
2.
` x + 2/5 = -11/15 `
`x = -11/15 - 2/5 `
`x = -17/15 `
vậy `x = -17/15 `