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a+b+c=18,iar 2a+b+2c=25,atuncicalculati (a+c)(3a+2b+3c)=

Răspuns :

   a+b+c=18
2a+b+2c=25
____________ adunam 
3a+2b+3c=43

2a+b+2c=25
 a+b+c=18
____________ scadem 
a+/+c=7 =>a+c=7

(a+c)(3a+2b+3c)=7*43=301