Question

Ma poate ajuta cineva cu acest ex?
Multumeeesc!❤
(n+1)!=5×n!+12×(n-1)!

Answer 1

(n+1)!=5•n!+12•(n-1)!

n≥1

(n+1)•n•(n-1)!=5•n•(n-1)!+12•(n-1)!      /: (n+1)!

(n+1)•n=5n+12

n²+n-5n-12=0

n²-4n-12=0

Δ=16+48=64

n1=(4+8)/2=6

n2=(4-8)/2= -2, nu convine

=>n=6