Đáp án:
Giải thích các bước giải:
Câu 1:
`a, 3 1/4 + (-5) . 1/5 - (-7 3/4 )`
= `3 + 1/4 - 1 + 7 + 3/4`
= `( 3 - 1 + 7 ) + ( 1/4 + 3/4 )`
= `9 + 1`
= `10`
`b, -1/2 - (-3/5 ) + (-1/9) + 1/27 + 7/18 + 4/35 - (-2/7)`
= `-1/2 + 3/5 - 1/9 + 1/27 + 7/18 + 4/35 + 2/7`
= `( -1/2 + 7/18 ) + ( 3/5 + 4/35 ) + ( 1/27 - 1/9 ) + 2/7`
= `-1/9 + 5/7 - 2/27 + 2/7`
= `1 - 5/27`
= `22/27`
`c, (4/17 - 4/49 + 4/31)/(3/17 - 3/49 + 3/31)`
= `(4. (1/17 - 1/49 + 1/31))/(3 . (1/17 - 1/49 + 1/31))`
= `4/3`
Câu 2:
`a, 3 - x = 1 1/4`
`3 - x = 5/4`
`x = 3 - 5/4`
`x = 7/4`
`b, x - 35%x = 13/2`
`x . ( 1 - 35% ) = 13/2`
`x . 13/20 = 13/2`
`x = 13/2 : 13/20`
`x = 10`
`c, 3 1/3x + 16 3/4 = 1,75`
`10/3x + 67/4 = 7/4`
`10/3x = 7/4 - 67/4`
`10/3x = -15`
`x = -15 : 10/3`
`x = -9/2`
