<< Graphics`ImplicitPlot`

ImplicitPlot[(x^2 + y^2 - 1) == 0, {x, -1, 
          1}];

ImplicitPlot[(x^2 - y) (y - x) (y^2 - x) == 
          0, {x, -0.5, 1.3}];

Solve[(x^2 - y) (y^2 - x) == 0, x]

Show[{ImplicitPlot[(x^2 - y) == 0, {x, -0.5, 
              1.3}],
ImplicitPlot[(y - x) == 0,{x, -0.5, 1.3},PlotStyle->Dashing[{0.05, 0.05}]],
ImplicitPlot[(y^2 - x) == 0,{x, -0.5, 1.3},PlotStyle->Dashing[{0.01, 0.01}]]
}]

ImplicitPlot[(x^2 + y^2 - 1) (x^2 - y^2 + 1) (-x^2 + 
              y^2 + 1) == 0, {x, -3, 3}, 
      PlotStyle -> Hue[1]]

(x^2 + y^2 - 1) (x^2 - y^2 + 1) (-x^2 + y^2 + 1) // 
      Expand