Question

5 calcule cu nr rationale

Answer 1

Stiim ca N ⊂  Z ⊂ Q 
(1) ...   1+2+3+...+10 = (1+10)+(2+9)+(3+8)+(4+7)+(5+6) = 5 * 11 = 55;
(2) ...  -1+2-3+4-5+6-7+8 = (2+4+6+8)-(1+3+5+7) = 20-16 = 4;
(3) ...   1/2+1/4+1/8 = (4*1+2*1+1)/8 =7/8 ;
(4) ...   0,1+0,2+0,3+0,4 = 1/10+2/10+3/10+4/10=(1+2+3+4)/10=10/10= 1;
(5) ...   (17-0,5)*2 : 3 + 11 - 12 = 33:3+11-12=11+11-12=22-12=10 ;