👤

a+b+c=18
2a+b+2c=25
Calculati: (a+c) x (3a+2b+3c)


Răspuns :

Scadem relatiile si le adunam:
25-18=a+c; a+c=7
3a+2b+3c=43
7×43=301
a+b+c=18
2a+b+2c=25
(a+c)(3a+2b+3c)=?  
a+b+c+2a+b+2c=18+25
3a+2b+3c=43
2a+b+2c-a-b-c=25-18
a+c=7
(a+c)(3a+2b+3c)=43*7=301