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Daca a,b,c sunt numere naturale astfel incat a+b+c=57 si 2a+b+2c=73. Calculati (a+c)·(5·a+2·b+5·c) .

Răspuns :

Danghinea74

a+b+c=57
a+c=57-b
2a+b+2c=73
2a+2c=73-b
2(a+c)=73-b
2(57-b)=73-b
114-2b=73-b
-2b+b=73-114
-b=-41
b=41
a+c=57-41=16

(a+c)(5a+2b+5c)
16(5(a+c)+2*41)
16(5*16+82)
16(80+82)
16*162
2592