Question

Urgent 17 va rog ! Dau coronita !

Answer 1

73=2a+b+2c=(a+b+c)+(a+c)=57+(a+c), deci  

a+c=16  

5a+2b+5c=2(2a+b+2c)+(a+c)=2*73+16=162 deci rezultatul cerut este:  

16*162=2592

Answer 2

17). a,b,c ∈ N

a+b+c=57

2a+b+2c=73

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(a+c)*(5a+2b+5c)=?

a+b+c=57 (inmultesc ecuatia cu -2) ⇒ -2a-2b-2c= -114

2a+b+2c=73

(adun ecuatiile)

-2a+2a-2b+b-2c+2c= -114+73

-b= - 41

b=41

a+41+c=57

a+c=57-41

a+c=16

acum mergem in ecuatia ce trebuie aflata si inlocuim:

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