Bài 7:
a, `A = 2^2 - (-3^2)^3 + 4^(-2) . 16 - 2 . 5^2`
`A = 4 - 3^6 + 1/16 . 16 - 2 . 25`
`A = 4 - 729 + 1 - 50`
`A = -774`
Vậy `A = -774`
b, `B = ( 2^3 : 1/2 ) . 1/8 + 3^(-2) . 9 - 7 . (14/25)^0 + 5`
`B = 8 . 2 . 1/8 + 1/9 . 9 - 7 . 1 + 5`
`B = 2 + 1 - 7 + 5`
`B = 1`
Vậy `B = 1`
Bài 8:
a, `(-5 . 7^5 + 7^4)/(7^6 . 10 - 2 . 7^5) = [7^4.(-5 . 7 + 1)]/[7^5 . 2 (7 . 5 - 1)]`
`= (-34)/(14.34)`
`= -1/14`
b, `(10^3 + 5 . 10^2 + 5^2)/(-13) = (1000 + 500 + 125)/(-13) = 1625/(-13) = -125`