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Wednesday, November 26, 2014

Sketching the Graph of a Polynomial, 6

Category: Analytic Geometry

"Published in Vacaville, California, USA"

Sketch the graph of a polynomial:


Solution:

Consider the given equation above  


Did you notice that the given equation is a perfect trinomial square? Let's factor the above equation as follows



and then it is factorable by the difference of two cubes as follows





If we set y = 0, then we can solve for the value of x at each factors which are the x-intercepts.

For , the value of x is





For , the value of x is 










Since the roots of the second factor are imaginary numbers, then we cannot accept those values. Because of this, the only x-intercept is 1.

If we set x = 0, the y-intercept of the given equation is   




Since we now the x-intercept, then we can sketch the location or direction of a curve as follows   

If x < 0, then y = (-)²(+)² = (+)
If 0 < x < 1, then y = (-)²(+)² = (+)
If x > 1, then y = (+)²(+)² = (+)

Here's the graph of a polynomial:  

Photo by Math Principles in Everyday Life