3.a+b=10
a-b=2=>a=b+2.
Inlocuim in prima ecuatie
b+2+b=10
b+b+2=10
2b=10-2
2b=8
b=8/2 ( adica 8 impartit la 2)
b=4
Si ziceam ca a=b+2,
deci a=4+2, a=6 ........
5.E(x)= {x-1-x²/x+2}*x+2/X-2
Aducem la acelasi numitor si obtinem:
{(x-1) (x+2) -x^2/x+2}*x+2/x-2
{x^2+2x-x-2-x^2/x+2}*x+2/x-2
x-2/x+2 * x+2 /x-2=1