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Example Questions
Example Question #25 : Zeros/Roots Of A Polynomial
Example Question #52 : Polynomial Functions
Example Question #51 : Polynomial Functions
Example Question #52 : Polynomial Functions
Example Question #53 : Polynomial Functions
Example Question #54 : Polynomial Functions
Example Question #55 : Polynomial Functions
Example Question #51 : Polynomial Functions
Consider the polynomial
Which of the following is true of the rational zeroes of ?
Hint: Think "Rational Zeroes Theorem".
is the only rational zero.
1 is the only rational zero.
and 1 are the only rational zeroes.
Neither nor 1 is a rational zero, but there is at least one rational zero.
There are no rational zeroes.
1 is the only rational zero.
By the Rational Zeroes Theorem, any rational zeroes of a polynomial must be obtainable by dividing a factor of the constant coefficient by a factor of the leading coefficient. Since both values are equal to 1, and 1 has only 1 as a factor, this restricts the set of possible rational zeroes to the set .
1 is a zero of if and only if . An easy test for this is to add the coefficients and determine whether their sum, which is , is 0:
1 is a zero.
is a zero of if and only if . An easy test for this is to add the coefficients after changing the sign of the odd-degree coefficients, and determine whether their sum, which is , is 0:
is not a zero.
1 is the only rational zero.
Example Question #52 : Polynomial Functions
The polynomial
has a zero on one of the following intervals. Which one?
The Intermediate value Theorem states that if is a continuous function, , and and are of unlike sign, it must hold that for some . Equivalently, if has values on the endpoints of an interval that differ in sign, then has a zero on that interval. Since all polynomial functions are continuous, we may apply this theorem by evaluating
for , and finding two consecutive values such that differs in sign.
By substitution, we can find that:
The change in sign occurs on the interval ; therefore, a zero of is located on this interval.
Example Question #53 : Polynomial Functions
Consider the polynomial
.
The Rational Zeroes Theorem allows us to reduce the possible rational zeroes of this polynomial to a set comprising how many elements?
By the Rational Zeroes Theorem, any rational zero of a polynomial with integer coefficients must be equal to a factor of the constant divided by a factor of the leading coefficient, taking both positive and negative numbers into account.
The constant 17, being prime, has only two factors, 1 and 17; the leading coefficient is 1, which only has 1 as a factor. Thus, the only possible rational zeroes of the given polynomial are given in the set
,
a set of four elements. This makes 4 the correct choice.