Răspunsuri

2014-08-17T16:20:41+03:00
X/5= c si r=3 => x=5c+3
x are 2 cifre , aflam valoarea maxima
5c+3<100 => 5c<97 => 5c=95 => c=19, valoarea max a lui x este 5*19+3, adica 98
c=0 => x=3
c=1 => x=8
c=2  => x=13,
Facem suma folosind formula pr arit
S = (13+98)*18/2=999
de ce ai luat catul < 9
<10
am presupus ca este format doar dintr-o singura cifra
Nu era specificat in problema si nu vad justificarea restrictiei pe care ai impus-o
am modificat, mi-am dat seama dupa aceea
2014-08-17T16:21:11+03:00
X:5=c1 rest 3
x=M₅ +3

1)x=5*1+3=5+3=8

2)x=5*2+3=10+3=13

3)x=5*3+3=15+3=18

4)x=5*4+3=20+3=23

5)x=5*5+3=25+3=28

6)x=5*6+3=30+3=33

7)x=5*7+3=35+3=38

8)x=5*8+3=40+3=43

9)x=5*9+3=45+3=48

10)x=5*10+3=50+3=53

11)x=5*11+3=55+3=58

12)x=5*12+3=60+3=63

13)x=5*13+3=65+3=68

14)x=5*14+3=70+3=73

15)x=5*15+3=75+3=78

16)x=5*16+3=80+3=83

17)x=5*17+3=85+3=88

18)x=5*18+3=90+3=93

19)x=5*19+3=95+3=98

Suma tuturor numerelor naturale de 2 cifre care impartite la 5 dau restul 3 este:

S=13+18+....+98

S=(13+98)*18/2

S=111 *9

S=999
10 4 10