# Showing an area from an Inequality under implicit curves

NilsP360 shared this question 1 year ago

When you have a function, lets say f(x)=x^2+1, then writing f(x)>1 does work, and shows you a (theoretically) infinite area that satisfies that inequality. However, with multivariable functions, this no longer works. For example, consider f(z), where z=x+y*i, where i^2=-1. Since complex numbers aren't ordered, you can't simply ask f(z)>2, but if we use the absolute value, it should give us a meaningful answer. You should be able to visualize the area on the complex plane that satisfies |f(z)|>2. I've calculated that this area can be written as the inequality (x² - y² + 1)² + (2x y)²>4, but if you try to do this in Geogebra, it just doesn't work. You can only show the implicit curve where you set (x² - y² + 1)² + (2x y)² = 4, giving you a 2D curve. The inequality (x² - y² + 1)² + (2x y)²>4 should then give you the area outside that implicit curve, and likewise, (x² - y² + 1)² + (2x y)²<4 should give you the area inside the implicit curve (x² - y² + 1)² + (2x y)²=4.

I dont know if this is a missing feature, or simply a bug, but either way, it would be very useful if you could fix it.

• plotting of 3D inequalities is not supported
• and plotting of 2D inequalities is limited

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• plotting of 3D inequalities is not supported
• and plotting of 2D inequalities is limited
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Shame, i can understand it wouldn't be easy to program it in, so i guess its understandable that such features aren't supported... I know programs like Desmos have this feature, would have been nice to have it in ggb too.

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Yea i agree. It is not the main purpose of this program though.

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en este caso puedes intentar -sqrt(1 - x² + 2sqrt(1 - x²)) ≤ y ≤ sqrt(1 - x² + 2sqrt(1 - x²))

pero creo que no será util en casos de iteración