Đáp án:
`a,`
`25 × (-1/5)^2 + 1/5 - 2 × (-1/2)^2 - 1/2`
`= 25 × 1/25 + 1/5 - 2 × 1/4 - 1/2`
`= 1 + 1/5 - 1/2 - 1/2`
`=6/5 - 1/2 - 1/2`
`= 7/10 - 1/2`
`= 1/5`
`b,`
`35 1/6 ÷ (-4/5) - 46 1/6 ÷ (-4/5)`
`= 35 1/6 × (-5/4) - 46 1/6 × (-5/4)`
`= (-5/4) × (35 1/6 - 46 1/6)`
`= -5/4 × (-11)`
`= 55/4`
`c,`
`(-3/4 + 2/5) ÷ 3/7 + (3/5 + (-1)/4) ÷ 3/7`
`= (-3/4+ 2/5) × 7/3 + (3/5 - 1/4) × 7/3`
`= 7/3 × [-3/5 + 2/5 + 3/5 - 1/4]`
`= 7/3 × [(-3/4 - 1/4) + (2/5 + 3/5)]`
`= 7/3 × [-1 + 1]`
`= 7/3 × 0`
`= 0`
`d,`
`7/8 ÷ (2/9 - 1/18) + 7/8 (1/16 - 5/12)`
`= 7/8 ÷ 1/6 + 7/8 × (-7/18)`
`= 21/4 - 49/144`
`= 707/144`
`e,`
`1/6 + 5/6 × 3/2 - 3/2 + 1`
`= 1/6 + 5/4 - 3/2 + 1`
`= 17/12 - 3/2 + 1`
`= (-1)/12 + 1`
`= 11/12`
`f,`
`(-0,75 - 1/4) ÷ (-5) + 1/15 - (-1/5) ÷ (-3)`
`= -1 ÷ (-5) + 1/15 - 1/15`
`= 1/5 + (1/15 - 1/15)`
`= 1/5 + 0`
`= 1/5`
