Question

a)daca a=15 si b-c=9 atunci ab -ac=.......
b)daca a+b=7 si c-b=25 atunci 103a+100b+3c=.......
c)daca a+2b+3c=20 si 3a+2b+c=16 ,aflati a+b+c=......

Answer 1

A) ab-ac=a(b-c)=15x9=135
B) a+b=7 si c-b=25 daca aduni cele 2relatii obtii:a+b+c-b=7+25-> a+c=32
103a+100b+3c=100a+3a+100b+3c=100(a+b)+3(a+c)=100x7+3x32=700+96= 796
C) a+2b+3c=20 si 3a+2b+c=16 adunam cele 2 relatii: a+2b+3c+3a+2b+c=20+16-> 4a+4b+4c=36-> 4(a+b+c)=36-> a+b+c=36:4=9