GeoGebra: Tangent Fields & Isoclines
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This applet displays tangent fields and coloured gradient fields for general solutions of explicitly defined 1st order ODE’s (i.e. dy/dx = …..)
It also displays the particular solution curve; you can set the boundary condition by dragging the blue point. [Euler's numerical method is used with error correction]
The applet also shows isoclines where possible [dy/dx=f(x,y) must be polynomial in x and y]