Question

Zbadaj monotoniczność ciągu (an )
A) an = -2n+20 B) an = 1+(-1)n C) an = n/(n+1)

Answer 1

a]an=-2n+20,an+1=-2[n+1]+20=-2n-2+20=-2n+18,an+1-an=-2n+18-[-2n+20]=18-20=-2

 

ciag malejacy

b]an=1+[-1]n

an+1=-1[n+1]+1=-n-1+1=-n+0

 

ciag malejacy

 

 

an+1-an=[-n+0]-[-n+1]=-1

c]