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ProMinecraft69
a fost răspuns

Sa se calculeze suma :
1/4-1/4*2+1/4*3-1/4*4 +....+1/4*15
* - la puterea

Răspuns :

Lucasela

S= 1/4-1/4^2+1/4^3-1/4^4 +....+1/4^15,  inmultim cu 4

=> 4S=1-1/4+1/4^2-1/4^3+.....+1/4^14

4S+S=(1-1/4+1/4^2-1/4^3+.....+1/4^14)+(1/4-1/4^2+1/4^3-1/4^4 +....+1/4^15)

5S=1+  1/4^15

S=(1+ 1/4^15)/5

S=[(4^15+1)/4^15]/5

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