Match each graph with its equation.
  1. x2+y2=4\displaystyle {x}^{{2}}+{y}^{{2}}={4}
  2. z+y+2x=4\displaystyle {z}+{y}+{2}{x}={4}
  3. z=x3\displaystyle {z}={x}^{{3}}
  4. z=x2\displaystyle {z}={x}^{{2}}