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  • Użytkownik Zadane
2010-02-27T01:23:58+01:00
A5=-5
a3+a8=-12

a1+4r=-5
a1+2r+a1+7r=-12

a1=-5-4r
2a1+9r=-12

a1=-5-4r
2(-5-4r)+9r=-12

a1=-5-4r
-10-8r+9r=-12

a1=-5-4r
r=-2

a1=3
r=-2


a1+a3=25
a2+a4=30

a1+a1*q²=25
a1*q+a1*q³=30

a1(1+q²)=25 /:(1+q²)
a1q(1+q²)=30

a1=25/(1+q²)
25q(1+q²)/(1+q²)=30

a1=25/(1+q²)
25q=30

a1=625/61
q=6/5