kto zrobi zadanie 11,12 z zalacznika daje NAJ!
11.
a1+r=2 /*(-1)
a1+6r=-3
-a1-r=-2
5r=-5a
r=-1
a1=3
an=3+(n-1)(-1)=3-n+1=-n+4
a100=-100+4=96 a150=-150+4=-164
S100=(3-94)/2 *100= -4650
S150=(3-146)/2 *150= -10 750
13.
an=5^n/7
a(n+1)=5^(n+1)/7
a(n+1)/an=5^(n+1)/7 * 7/ 5^n=5^(n+1)/5^n=5^n*5/5^n=5 zatem ciąg jest geometryczny
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11.
a1+r=2 /*(-1)
a1+6r=-3
-a1-r=-2
a1+6r=-3
5r=-5a
r=-1
a1=3
an=3+(n-1)(-1)=3-n+1=-n+4
a100=-100+4=96 a150=-150+4=-164
S100=(3-94)/2 *100= -4650
S150=(3-146)/2 *150= -10 750
13.
an=5^n/7
a(n+1)=5^(n+1)/7
a(n+1)/an=5^(n+1)/7 * 7/ 5^n=5^(n+1)/5^n=5^n*5/5^n=5 zatem ciąg jest geometryczny