Question

calculati2a+5b+3c,stiind ca a+b=3sib+c=5

Answer 1

2a+5b+3c=?<br />a+b=3<br />b+c=5<br />2a+2b=6<br />3b+3c=15<br />2a+2b+3b+3c=6+15<br />2a+5b+3c=21

Answer 2

2a+5b+3c=(2a+2b)+(3b+3c)

a+b=3 deci 2(a+b)=6

b+c=5 deci3(b+c)=15 , inlocuim in prima ecuatie si avem

6+15=21