Question

Resolva a equação 5 . {n!/(n-3)! = n!/(n-4)!}

Answer 1

5.n/(n-3)= n/(n-4)
5n/n-3=n/n-4 
5n²-20n=n²-3n
5n²-n²-20n+3n=0 
4n²-17n=0 
Δ=289
17+-√289/8=0
17+-17/8=0
n'=17+17/8=34/8=17/2
n''= 0