a fost răspuns

daca a+b=20 si b+c=30 , calculati 3a+7b+4c.
daca a+b=33 si a+c=11 , calculati 5a+3b+2c.

Răspuns :

3a+7b+4c= 3(20-b)+7b+4(30-b) = 60-3b+7b+120-4b=180
5a+3b+2c= 5a + 3(33-a) + 2(11-a) = 5a+99-3a+22-2a = 121
Mgeana02ask
20+20+20+30+30+30+30=180
3a+7b+4c=180
33+33+33+11+11=99+22=121
5a+3b+2b=121