Question

Daca A+B=999,iar A-B=1,afla ce valoare are .Dar b?

Answer 1

a+b=999
a-b=1
------------
a+b+a-b=999+1
2a=1000
a=1000:2
a=500
b=999-500
b=499

Answer 2

[tex] \left \{ {a+b=999} \atop {a-b=1}} \right. =\ \textgreater \ 2a=1000=\ \textgreater \ a=500\\ ---------\\ 500+b=999=\ \textgreater \ b=999-500=\ \textgreater \ b=499\\ ----------\\ a+b=999\ \textless \ =\ \textgreater \ 500+499=999(corect)\\ a-b=1\ \textless \ =\ \textgreater \ 500-499=1(corect)[/tex]