C
changtrajcualua


a) [tex]\ x^3+2x+sqrt{x+1}=5 [/tex]
b)
[tex]\left\{ \begin{array}{l} x+\sqrt{y} = 1 \\ x - y^x =3 \end{array} \right.[/tex]
b)
[tex]\left\{ \begin{array}{l} x+\sqrt{y} = 1 \\ x - y^x =3 \end{array} \right.[/tex]