Bài `2:`
`a)`
`(-5/9)^10 : x = (-5/9)^5`
`=> x= (-5/9)^10 : (-5/9)^5`
`=> x = (-5/9)^5`
`=> x = -3125/59049`
Vậy `x = -3125/59049`
`b)`
`x : (-5/9)^5= (-9/5)^5`
`=> x = (-9/5)^5 . (-5/9)^5`
`=> x = ((-9)/5 . (-5)/9 )^5`
`=> x = 1^5`
`=> x = 1`
Vậy `x=1`
`c)`
`x^3 = -8`
`=> x^3 = (-2)^3`
`=> x = -2`
Vậy `x=-2`
`d)`
`(x+5)^3 = -27`
`=> (x+5)^3 = (-3)^3`
`=> x + 5 = -3`
`=> x =- 3 - 5`
`=> x =-8`
Vậy `x=-8`
`e)`
`(2x-3)^3 = -64`
`=> (2x-3)^3 = (-4)^3`
`=> 2x - 3 = -4`
`=> 2x = -1`
`=> x = -1/2`
Vậy `x=-1/2`
`f)`
`(2x-3)^2 = 25`
`=> (2x-3)^2 = (+-5)^2`
`=> 2x-3=5` hoặc `2x-3 = -5`
`+) 2x - 3 = 5 => 2x = 8 => x = 4`
`+) 2x - 3 = -5 => 2x = -2 => x = -1`
Vậy `x \in {4;-1}`
