Răspuns:
cmmdc = 1
Explicație pas cu pas:
7 prieteni = a , b , c , d , e , f , g
minim 2 note diferite => f ≠ g ≠ (a,b,c,d,e)
a + b + c + d + e + f + g = 49 =>
(a,b,c,d,e) ≠ 10
5a + f+g = 49
a = b = c = d = e = 9 =>
5·9+f+g = 49 => f+g = 4 => f = 1 ; g = 3
cmmdc ( 1 ; 3 ; 9) = 1
a = b = c = d = e = 8 =>
5·8+f+g = 49 => f+g = 9 => f = 4 ; g = 5
cmmdc(8 ; 4 ; 5) = 1
f+g = 9 => f = 3 ; g = 6
cmmdc(8 ; 3 ; 6) = 1
f+g = 9 => f = 2 ; g = 7
cmmdc(8 ; 2 ; 7) = 1
a = b = c = d = e = 7 =>
5·7 + f+g = 49 => f+g = 14 => f = 10 ; g = 4
cmmdc(7 ; 10 ; 4) = 1
f = 9 ; g = 5 ;
f = 8 ; g = 6 ;
cmmdc = 1
a = b = c = d = e =6 =>
5·6+f+g = 49 => f+g = 19 => f = 10 ; g = 9
cmmdc(6;10;9) = 1
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