Đáp án + Giải thích các bước giải:
Bài `28`:
`(-1/4)^0 = 1`
`(-2 1/3)^2 = ( -7/3)^2`
` = ((-7)^2)/(3^2) = 49/9`
`(0,5)^3 = (1/2)^3`
` = (1^3)/(2^3) = 1/8`
`(-1 1/3)^4`
` = (-4/3)^4`
` = ( (-4)^4)/(3^4)`
` = 256/81`
Bài `29`: Tìm x, biết rằng:
a, `x : ( -1/3)^3 = -1/3`
` x = (-1/3) . (-1/3)^3`
` x = (-1/3)^4`
` x = 1/81`
Vậy `x = 1/81`
b, `(4/5)^5 . x = (4/5)^7`
` x = (4/5)^7 : (4/5)^5`
` x = (4/5)^2`
` x = 16/25`
Vậy `x = 16/25`
c, `(x + 1/2)^2 = 1/16`
` (x + 1/2)^2 = (1/4)^2 = (-1/4)^2`
⇒\(\left[ \begin{array}{l}x + \frac{1}{2} = \frac{1}{4}\\x + \frac{1}{2} = -\frac{1}{4}\end{array} \right.\)
⇒\(\left[ \begin{array}{l}x = -\frac{1}{4}\\x = -\frac{3}{4}\end{array} \right.\)
Vậy `x \in { -1/4 ; -3/4}`
d, `(3x + 1)^3 = -27`
`(3x + 1)^3 = (-3)^3`
`⇒ 3x + 1 = -3`
` 3x = -3 - 1`
` 3x = -4`
` x = -4/3`
Vậy `x = -4/3`
