Question

A+b+c=7 si 4*a+3*b+2*c=18.calculeaza: (5*a+4*b+3*c)*(3*a+2*b+c)

Answer 1

[tex]a+b+c=7\\4a+3b+2c=18\\\text{Dac\u a adun\u am cele dou\u a rela\c tii, avem c\u a: }\\ 5a+4b+3c=(a+b+c)+(4a+3b+2c)=7+18=25\\\text{Iar dac\u a din a doua rela\c tie, o sc\u adem pe prima, avem c\u a: }\\3a+2b+c=(4a+3b+2c)-(a+b+c)=18-7=11\\ (5a+4b+3c)(3a+2b+c)=25\cdot11=275[/tex]