1) 0,8 ^ 1/7 = ( 4/5 ) ^ 1/7 = ( 2 ^ 2) ^ 1/7 • ( 5 ^ - 1 ) ^ 1/7 = ( 2^2/7 )•( 5 ^ - 1/7 )
2) 20 ^ 6/7 = ( 2^2 •5 ) ^6/7 = ( 2 ^ 12/7 )•( 5 ^6/7 )
3) (2^2/7)•(5^-1/7)•(5^2/7 ) = ( 2^2/7 )•( 5^1/7 )
4) (2^2/7)•(5^1/7)•( 2^12/7)•(5^6/7 ) = ( 2^14/7)•(5^7/7) = ( 2^2 )•5 = 4•5 = 20
Ответ 20