Đáp án:
Giải thích các bước giải:
bài 1
` 1/12 +(-11/12)=-10/12= -5/6`
` (2/5)^9 : (2/5)^6= (2/5)^3 = 8/125`
` 1/2 . (6/7)^0 +[ 1 1/2- 27.(1/3)^4]= 1/2.1+[3/2-27. (1/81)]= 1/2+[3/2-1/3]= 1/2+7/6=5/3`
câu 2
a)
`x: (2/3)^2= (2/3)^3`
`x =(2/3)^3 . (2/3)^2`
`x= (2/3)^5`
`x= 32/243`
b)
`|x-3/7| + 1/12= 1/8 `
` |x-3/7| = 1/8 - 1/12 `
`| x-3/7| =1/24`
`⇒ x-3/7= ±1/24`
*`x-3/7= 1/24`
` x= 1/24+3/7`
` x= 79/168`
* `x-3/7 = -1/24`
` x= -1/24+3/7`
` x= 65/168`
vây `S ={ 79/168; 65/168}`