Question

calculati suma primilor 2023 termeni ai progresiei aritmetice stiind ca:
a1 =-1/3 si r= 1/2

Answer 1

S2023= [(a1+a2023)*2023]/2

a2023 = a1+ 2022r = -1/3 + 2022*1/2 = -1/3 + 1011 = -1/3 + 3033/3 = 3032/3

S2023 = [(-1/3+3032/3)*2023]/2 = [3031/3*2023]/2 = 6131713/3 * 1/2 = 6131713/6

Answer 2

Răspuns:

Sn=(a1+an)n/2

an=a1+(n-1)r

a2023=-1/3+(2023-1)/2=-1/3+1011=3032/3

S2023=(-1/3+3032/3)2023/2=(3031/3)(2023/2)=(3031*2023)/6

Explicație pas cu pas: