Đáp án + Giải thích các bước giải:
`b)` `(-4/9 + 3/5) : 1 1/5 + (1/5 - 5/9) : 1 1/5`
`= (-4/9 + 3/5) : 6/5 + (1/5 - 5/9) : 6/5`
`= (-4/9 + 3/5) . 5/6 + (1/5 - 5/9) . 5/6`
`= (-4/9 + 3/5 + 1/5 - 5/9) . 5/6`
`= [(-4/9 - 5/9 )+ (3/5 + 1/5)] . 5/6`
`= [-1 + 4/5] . 5/6`
`= (-1)/5 . 5/6`
`= (-1)/6`
`c)` `(4^25 . 5^21)/(25^11 . 2^48)`
`= ((2^2)^25 . 5^21)/((5^2)^11 . 2^48)`
`= (2^50 . 5^21)/(5^22 . 2^48)`
`= (2^2)/(5)`
`= 4/5`
`d)` `(2^7 . 9^3)/(6^5 . 8^2)`
`= (2^7 . (3^2)^3)/((2.3)^5 . (2^3)^2)`
`= (2^7 . 3^6)/(2^5 . 3^5 . 2^6)`
`= (2^7 . 3^6)/(2^11 . 3^5)`
`= (3)/(2^4)`
`= 3/16`
