Question

Va rog... . Ajutati-ma!

Calculati sumele:

a)
S=100+104+108+...+500
b)
S=36+40+44+...+436
c)
S=1005+1010+1015+...+2000
d)
S=860+890+920+...+1490
e)
S=18+33+48+...+753
f)
S=9+16+23+... 149

Answer 1

a)S=100+104+108+..+500 =>Pasul: 104-100=4 108-104=4
Nr. de termeni : (500-100):4+1=400:4+1=100+1=101 termeni
Suma: [(100+500)×101]:2=(600×101):2=60600:2=30300

b)S=36+40+44+...+436 =>Pasul:40-36=4 44-40=4
Nr. de termeni: (436-36):4+1=400:4+1=100+1=101 termeni
Suma: [(36+436)×101]:2=(472×101):2=47672:2=23836

Teorie:
Prima data afli Pasul.
Numărul de termeni : (ultimul-primul):pas+1
Suma : [(primul+ultimul)×numarul de termeni]:2
Sper ca te-am ajutat .