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Implicit Graphing on TI-Nspire CAS

## Implicit Graphing on TI-Nspire CAS

Implicit graphing of relations in two variables is possible with TI-Nspire CAS, using the

zeroscommand. In the Calculator, zeros(x^{2}-y^{2}-4,y) will take an expression in two variables and return as a list, where possible, the symbolic forms of the function with y isolated. Graphs & Geometry can graph such a list of functions, and so we see the implicit plot.The video shows the syntax and some of the possibilities for this form.

For non-CAS, the same effect is possible using the

nSolvecommand, although the method is much slower, especially on the handheld. For example, to plot the hyperbola, x^{2}- y^{2}= 4, define:f1(x) = nSolve(x

^{2}- y^{2}= 4,y)f2(x) = nSolve(x

^{2}- y^{2}= 4,y=-2)nSolve takes an equation as its argument, while zeros requires an expression. nSolve will always require multiple applications to achieve a complete curve.

An application of this method uses a simple function called

fiveptconic(available from the add2cas library) which takes coordinates of five points and plots the conic which passes through these.©2009 Compass Learning Technologies ←Home ← TI-Nspire Authoring ←

Implicit Graphing on TI-Nspire CAS