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Monday, February 25, 2013

Graphical Sketch - Polynomials

Category: Analytic Geometry, Algebra

"Published in Suisun City, California, USA"

Sketch the graph for



Solution:

The first thing that we have to do is to factor the given equation by synthetic division as follows


Photo by Math Principles in Everyday Life

The x-intercepts are -1, 1, 2, and 3. To get the y-intercept, set x = 0 to the given equation, we have







Now, plot the points -1, 1, 2, and 3 along the x-axis and 6 along the y-axis. These points will pass the curve. To get the direction of the curve, let's consider the following



if    x < 3,       then y = (-)(-)(-)(-) = (+)
   - 3 < x < -1, then y = (-)(-)(+)(-) = (-)
    -1 < x < 1,  then y = (+)(-)(+)(-) = (+)
     1 < x < 2,  then y = (+)(-)(+)(+) = (-)
     x > 2,        then y = (+)(+)(+)(+) = (+)

Connect all the points and the graph must be like this


Photo by Math Principles in Everyday Life