Đáp án:
Bài `1`
`a,`
`4 × (-1/2)^3 + 1/2 ÷ 5`
`= 4 × (-1/8) + 1/2 × 1/5`
`= (-1)/2 + 1/10`
`= (-2)/5`
`b,`
`-1^3 × \sqrt{81} + 5 3/4 + (-1/2)^2`
`= -1 × 9 + 23/4 + 1/4`
`= 9 + 23/4 + 1/4`
`= 59/4 + 1/4`
`= 115`
$\\$
Bài `2`
`a,`
`2 2/3 ÷ x = 1 7/9 ÷ 0,02`
`-> 8/3 ÷ x = 16/9 ÷ 0,02`
`-> 8/3 ÷ x = 800/9`
`-> x= 8/3 ÷ 800/9`
`-> x = 3/100`
Vậy `x = 3/100`
`b,`
`2 (x + 1)^3 + 4 =58`
`-> 2 (x + 1)^3 = 58 - 4`
`-> 2 (x + 1)^3 = 54`
`-> (x + 1)^3 = 54 ÷ 2`
`-> (x + 1)^3 =27`
`-> (x + 1)^3 = 3^3`
`-> x + 1 = 3`
`-> x = 3 - 1`
`-> x = 2`
Vậy `x=2`
