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Polynomial with degree Four

One Zero

For example, f(x)=x4 or tex2html_wrap_inline12 the graph will be similar to g(x)=x2 or tex2html_wrap_inline16 This is because if x is a large number (say 100), f(100) will be a positive number, and notice that f(-100)>0 too. On the other hands, f(x)=-x4 or tex2html_wrap_inline28 the graph will be similar to g(x)=-x2 o r tex2html_wrap_inline32 This is because if x is a large number (say 100), f(100) will be a negative number, and notice that f(-100)<0 too.

Example: Compare f(x)=x2 and g(x)=x4

Two Zeroes

Case 1:

Example: Sketch the graph of tex2html_wrap_inline46.

 Notice that f touches two zeroes at x=2 and 3. This is because the multiplicities of x=2 and x=2 are equal to 2.

Case 2.

Example: Sketch the graph of tex2html_wrap_inline60.

Notice that f is ''crossing'' at x=0 and x=1, but there is a little turn between x=0 and x=1. (It is not quite exactly like y=x4) We do not worry about this until we study ''calculus''.

Three Zeroes

Example: Sketch tex2html_wrap_inline74.

Four Zeroes

Example: Sketch tex2html_wrap_inline76.


Wei-Chi Yang

Tue Nov 5 21:20:17 EST 1996