Porisma

A hint to get started

Recover a cubic from its graph

A cubic polynomial curve, CC, is shown below, find a possible equation for CC.

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Source cubic grid: x-axis labelled from −4 to 6; y-axis levels −2,−1,0,1. Curve crosses x at −3,2,5 and y at −2, rises to the left and falls to the right.
Source cubic grid: x-axis labelled from −4 to 6; y-axis levels −2,−1,0,1. Curve crosses x at −3,2,5 and y at −2, rises to the left and falls to the right.
Source cubic grid: x-axis labelled from −4 to 6; y-axis levels −2,−1,0,1. Curve crosses x at −3,2,5 and y at −2, rises to the left and falls to the right.

CJC · Lecture · Example 7

The intercepts determine three factors and one remaining multiplicative constant.

Read the worked solution