Verified answer

Объяснение:

А = 6!×4!/8!(7!/3!×5! - 8!/2!×6!) = 6!×4!/8!(7×6×5!/3!×5! - 8×7×6!/2!×6!) = 6!×4!/8!(42/3×2! - 56/2!) = 6!×4!/8! × (-126/3!) = 6!×4!/8×7×6! × (-21) = -3×4!/8 = -3×24/8 = -9

В=(9!-7!)/71 = (9×8×7!-7!)/71 = (72×7!-7!)/71=71×7!/71 = 7! = 5040

С=90!/91! + 29!/28! = 90!/91×90! + 29×28!/28! = 1/91 + 29 = 29 1/91

Ответ: А=-9; С=29 1/91; В=5040.