Đáp án:
Giải thích các bước giải:
`a. (2x + 4/5) \div 7/20 - 2 1/3 = 5 2/3`
`-> (2x + 4/5) \div 7/20 - 7/3 = 17/3`
`-> (2x + 4/5) \div 7/20 = 17/3 + 7/3`
`-> (2x+4/5) \div 7/20 = 8`
`-> 2x + 4/5 = 8 xx 7/20`
`-> 2x + 4/5 = 14/5`
`-> 2x = 10/5`
`-> 2x = 2`
`-> x = 1`
Vậy `x \in {1}`
`b. (-4)/30 - (x/3 + 1/2)^3 \div 5/36 = (-1)/6`
`-> (x/3+1/2)^3 \div 5/36 = 1/6 - 4/30`
`-> (x/3+1/2)^3 \div 5/36 = 1/30`
`-> (x/3 + 1/2)^3 = 1/30 \div 5/36`
`-> (x/3+1/2)^3 = 1/216`
`-> (x/3+1/2)^3 = (1/6)^3`
`-> x/3 + 1/2 = 1/6`
`-> x/3 = 1/6 - 1/2`
`-> x/3 = -1/3`
`-> x = -1`
Vậy `x \in {1}`
`c. 1/3(x+2) - 2/3(x-1) = 0`
`-> 1(x+2) - 2(x-1) = 0`
`-> x + 2 - 2x + 2 = 0`
`-> -x + 4 = 0`
`-> -x = -4`
`-> x = 4`
Vậy `x \in {4}`
