. Вычислить 1. (7!+6!+5!)/( 8!-7!) 2. 9!/5!*4! 3. n! / n ( n-1 )
1. (7!+6!+5!)=5!*(6*7+6+1)=5!*49 (8!-7!)=7!*(8-1)=7!*7=6!*49 (7!+6!+5!)/( 8!–7!)= (5!*49)/(6!*49)=5!/(5!*6)=1/6 2. 9!/(5!·4!)=(6*7*8*9)/(4!)=(6*7*8*9)/24=126 3. n! / n ( n–1 ) = ((n-1)!*n)/(n*(n-1))=(n-1)!/(n-1)=(n-2)!