am nevoie va implor mult.
Răspunsuri la întrebare
Răspuns:
12. a) 12,14,16,18,24,26,28,34,36,38,46,48,56,58,68,78=> 12+14+16+18+24+26+28+34+36+38+46+48+56+58+68+78=544
b) 13+15+17+19+23+25+27+29+35+37+39+45+47+49+57+59+67+69+79+89=817
13. a) a+b =37 ; a+2b=54=> b+(a+b)=54=> b+37=54=> b=17=> a=37-17=20
b) a+b=19 si b+3c=30 => a+2b+3c=a+b+b+3c=19+30=49
c) a+b= 23
d) a+b=23 si 2a-b=7=> scoatem b si ramanem:
a+2a=23+7=>3a=30=>a=10
14. 57+10-1=67-1=66
77+20-9=97-9=88
145+100-1=245-1=244
375+100+1=475+1=476
4326+1000-2=5326-2=5324
7027+1000+2=8027+2=8029
15. a) 9+6+11=15+11=26
b) 17+99+1+83=116+1+83=117+83=200
c) 734+1345+266+655=2079+266+655=2345+655=3000
d) (233+989)+67+11=1222+67+11=1289+11=1300
e)(98+347)+(153+2)=445+155=600
16. 57-10+1=47+1=48
77-11=77-20+9=57+9=66
145-99=145-100+1=46
375-101=375-200+99=175+99=274
4326-998=4326-1000+2=3326+2=3328
7027-1002=7027-2000+998=5027+998=6025