Đáp án:
Câu 1 :
a, 115 - (-85)+ 53 - (2²-3²)+(-2017)∧0
= 115 - (-85)+53-(4-9)+0
= 115 - (-85) +53-(-5)
= 200 + 53-(-5)
= 253-(-5)
= 258
b,( `2/3` - `5/6` + `3/4` ) : `(-35)/24`
=( `(-1)/6` + `3/4` ) : `(-35)/24`
= `7/12` : `(-35)/24`
= `2/(-5)`
c, 75% - ( 1 - `3/4`) . `2/3 - `8/7`. ( `1/2` )²
= `75/100` - `1/4` . `2/3` - `8/7` . `1/4`
= `1/2` - `1/6` - `2/7`
= `1/3` - `2/7`
=`1/21`
d,[( 2 `1/2` - 0,25 ) : `3/8` - `5/3` ] - ( `2/3` )²
=[( `5/2` - `1/4` ) : `3/8` - `5/3` - `4/9`
= `9/4` : `3/8` - `5/3` - `4/9`
= 6 - `5/3` - `4/9`
=`13/3` - `4/9`
=`35/9`
Câu 2 :
a, `7/8` + 2,5x = `5/6`
2,5x = `5/6` - `7/8`
2,5x = `(-1)/24`
x = `(-1)/24 : 2,5
x = `(-1)/60`
b, 2( x - `1/3`) = `5/9`
x -`1/3` = `5/9` : 2
x - `1/3` = `10/9`
x = `10/9` + `1/3`
x = `13/9`
c,4-(`1/2`x + `3/4`) = -1,5
`1/2` x + `3/4` = 4-(-1,5)
`1/2` x + `3/4` = `5/2`
`1/2` x = `5/2` - `3/4`
`1/2` x = `7/4`
x = `7/4` : `1/2`
x = `7/2`
xin hay nhất ! Mệt quá !!!
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