Q&A #758

Graph of a cubic equation

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From: Marielouise (for Teacher2Teacher Service)
Date: Nov 09, 1998 at 16:39:48
Subject: Graph of a cubic equation

Hi, Toon, No, I cannot draw a graph of a cubic equation, because I do not have the capability with this email software. However, I think that if I describe a cubic equation's graph, you might be able to draw one. Take the following coordinates and locate them on a grid. (-4, -12) (-3,0) (-2, 4), (-1,3), (0,0) (1, -4) (2,0) (3, 9). Starting on the left side of the grid draw a line that passes through all of these points in sequence as you go from left to right. You will notice that the graph has a high point (or mountain) followed by a deep valley followed by a rise up again. Every graph of a cubic equation has a high point and a valley or is shaped like an s-shaped curve. If you have access to a graphing calculator or a computer, graph: y = .5x(x+3)(x-2). Also graph y = x(x+1)(x-1) as well as y=.5x^3. All of these are cubics. -Marielouise, for the Teacher2Teacher service

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