Question

Calcule :P7 - 4 ( P5 + P3 ) =C 7,3 + C 9,5=

Answer 1

Boa tarde 

P7 - 4*(P5 + P3) = 

P(n) = n!

7! - 4*(5! + 3!) = 5040 - 4*(120 + 6) = 5040 - 4*126 = 4536 

C(n,k) = n!/k!(n-k)!

C(7,3) = 7!/3!4! = 7*6*5/6 = 35
C(9,5) = 9!/5!4! = 9*8*7*6/4! = 63*48/24 = 126 

C(7,3) + C(9,5) = 35 + 126 = 161