10) c.m.m.d.c.= 40 = 2³ × 5
=> perechile : a= 2³×5×3 = 120 ; a= 2³×5×5 = 200 ; a= 2⁴×5= 90 ;
b= 2³×5×7 = 280 ; b= 2³×5×7 = 280 ; b= 2³×5= 40 ;
17) 30 < n < 50 = 30<[3;6;8]<50 + 1 = 2*24+1=49 pentru ca 3 = 3
6 = 2*3
8 = 2³
------------
[3;6;8] = 24 !!!