Q:        Why does x^(1/3) not plot for negative x?

A:        The principal cube root of a negative number is complex and cannot be plotted directly.  Use the Branch fieldBranch_field on the Simplification tab of the algebra window’s Options > Mode Settings command19_L5FP to make Derive select the real branch instead of the principal branch while plotting.


Q:        When I try to plot a vector of two expressions the 2D-plot window, why does Derive not plot them correctly?

A:        Derive plots a vector of two univariate expressions parametrically (see Parametric PlotsParametric_Plots).  However, you can add ? as a dummy third element to the vector so Derive produces the multiple plot you desire.


Q:        In the 2D-plot window, how do I make x²+y² = 4 plot like a circle instead of an ellipse?

A:        Issue the Set > Aspect Ratio command02_MF4, and click on the Reset button and then the OK button to make the physical distance between horizontal and vertical tick marks the same.


Q:        How can I make a 3D plot of two intersecting surfaces?

A:        Highlight and plot the expression defining the first surface in the 3D-plot window.  Then return to the algebra window, and highlight and plot the expression defining the second surface.  Rotating the plots will help you visualize the intersection better.  Also increasing the number of grid intervals of both plots makes the intersection clearer.


Other Frequently Asked Questions and AnswersFrequently_Asked_Questions_and_Answers 

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