Question

Daca Ab +ba= 90,cat e a si cat e b,știind ca a-b=3

Answer 1

ab+ba=90
a=? b=?
a-b=3=>a=b+3

(b+3)b+b(b+3)=90
2b(b+3)=90
2b^2+6b=90
2b^2+6b-90=0
delta=36+720=756.......de aici calculam b si aflam pe a in fct de b