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Example Questions
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.
Example Question #61 : Polynomial Functions
Consider the polynomial
.
Going by Descartes' Rule of Signs alone, how many positive real zeroes could the polynomial have?
One or three
Exactly one
Exactly two
Exactly three
None or two
None or two
By Descartes' Rule of Signs, the number of positive real zeroes of a polynomial with real coefficients is, at maximum, the number of its sign changes, but equal to some number of the same odd-even parity. This number can be seen to be two:
This means that this polynomial must have either zero or two such zeroes.
Example Question #231 : College Algebra
If the function is depicted here, which answer choice graphs ?
Example Question #62 : Polynomial Functions
Which of the following graphs correctly represents the quadratic inequality below (solutions to the inequalities are shaded in blue)?
To begin, we analyze the equation given: the base equation, is shifted left one unit and vertically stretched by a factor of 2. The graph of the equation is:
To solve the inequality, we need to take a test point and plug it in to see if it matches the inequality. The only points that cannot be used are those directly on our parabola, so let's use the origin . If plugging this point in makes the inequality true, then we shade the area containing that point (in this case, outside the parabola); if it makes the inequality untrue, then the opposite side is shaded (in this case, the inside of the parabola). Plugging the numbers in shows:
Simplified as:
Which is not true, so the area inside of the parabola should be shaded, resulting in the following graph:
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