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**Unformatted text preview: **rmination of the zeros of f and
their multiplicities, we know the graph crosses at x = − 26 ≈ −1.22 then turns back upwards to
touch the x−axis at x = −1. This tells us that, despite what the calculator showed us the ﬁrst time,
there is a relative maximum occurring at x = −1 and not a ‘ﬂattened crossing’ as we originally 210 Polynomial Functions believed. After resizing the window, we see not only the relative maximum but also a relative
minimum just to the left of x = −1 which shows us, once again, that Mathematics enhances the
technology, instead of vice-versa. Our next example shows how even a mild-mannered polynomial can cause problems.
Example 3.3.4. Let f (x) = x4 + x2 − 12.
1. Use Cauchy’s Bound to determine an interval in which all of the real zeros of f lie.
2. Use the Rational Zeros Theorem to determine a list of possible rational zeros of f .
3. Graph y = f (x) using your graphing calculator.
4. Find all of the real zeros of f and their multiplicities.
Solution.
1. Applying Cau...

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