f injectiva daca oricare ar fi y apartinand lui [-1,3] ecuatia f(x)=y are solutia x apartinand lui [0,2]
f(x)=y=>f(0)=-1=>0*a+b=-1=>b=-1
f surjectiva daca oricare ar fi y apartinand lui [-1,3] ecuatia f(x)=y are solutia x apartinand lui [0,2]
f(x)=y=>f(2)=-3=>2*a+b=-3=>2a=-3+1=>a=-1