4 min read Jun 17, 2024

Exploring the Implicit Equation: (x^2 + y^2)^2 = 4x^2y

The equation (x^2 + y^2)^2 = 4x^2y represents a fascinating curve in the xy-plane. It's an implicit equation, meaning it's not explicitly solved for either x or y. This makes it challenging to graph directly but also reveals intriguing properties and symmetries. Let's delve into its characteristics:

Understanding the Equation

  • Symmetry: The equation is symmetric about both the x-axis and the y-axis. This is evident because replacing x with -x or y with -y doesn't change the equation.
  • Origin: The curve passes through the origin (0, 0) as substituting x = 0 and y = 0 satisfies the equation.
  • Polar Coordinates: The equation simplifies in polar coordinates. Substituting x = r cos(θ) and y = r sin(θ) gives: (r^2)^2 = 4(r cos(θ))^2(r sin(θ)) This reduces to r^4 = 4r^3 cos^2(θ)sin(θ).

Visualizing the Curve

The shape of the curve can be visualized using tools like graphing calculators or online plotting software. It resembles a lemniscate with two loops, similar to the infinity symbol (∞). The loops are symmetrical about the origin and extend outward along the x-axis.

Analyzing the Curve

  • Intersection with Axes: The curve intersects the x-axis at x = ±2. This can be found by setting y = 0 in the equation. However, the curve does not intersect the y-axis.
  • Asymptotes: The curve has no asymptotes. As x or y approaches infinity, the left-hand side of the equation becomes much larger than the right-hand side. This indicates the curve doesn't approach any specific line.
  • Singularities: The curve exhibits singularities at the origin. These are points where the derivative is undefined.


The curve described by this equation has applications in:

  • Mathematics: It serves as a useful example for studying implicit equations, symmetry, and polar coordinate systems.
  • Physics: The curve can be used to model certain physical phenomena. For instance, it may be related to the shape of certain force fields.
  • Engineering: The curve may find applications in areas like design and optimization.


While the equation (x^2 + y^2)^2 = 4x^2y appears complex at first, its analysis reveals fascinating properties. It's a great example of an implicit equation that showcases the power of mathematical tools to understand and visualize intricate curves. Further exploration of this curve can lead to deeper insights into its behavior and its applications in diverse fields.

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