a) x=(1+2+3+..+98)+49
x=98*99+49
2
Putem efectua si astfel;
x=49*99+49
Daca dam factor comun 49, avem:
x=49*(99+1)
x=49*100
x=4900
b)x=1+3+5+...+225
x=(225+1)*[(225-1):2+1]
2
x=226*(112+1)
2
x=226*113
x=25538
Si asa mai departe. Aplici tu formulele:
Suma=(U+P)*nr termeni
2
Nr termeni=(U-P):Ratie(din cat in cat e sirul)+1