Răspunsuri

  • Utilizator Brainly
2014-06-28T21:17:41+03:00
F(1)=5, f(2)=7, f(3)=9, f(4)=11,f(5)=13, f(6)=15 ,f(7)=17, f(8)=19, f(9)=21, f(10)=23. 5+7+9+11+13+15+17+19+21+23=140
Data viitoare sa dai mai multe puncte. Bine? :)
Se face mult mai usor daca consideri sirul a fi o progresie aritmetica,cum a facut si Miky93
2014-06-28T22:11:49+03:00
F(1)=2*1+3=2+3=5
f(2)=2*2+3=4+3=7
f(3)=2*3+3=6+3=9
................................
f(9)=2*9+3=18+3=21
f(10)=2*10+3=20+3=23

S=(5+23)*10/2

S=28*10/2

S=14*10

S=140
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