College Algebra : College Algebra

Study concepts, example questions & explanations for College Algebra

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Example Questions

Example Question #52 : Polynomial Functions

Possible Answers:

Correct answer:

Explanation:

Example Question #53 : Polynomial Functions

Possible Answers:

Correct answer:

Explanation:

Example Question #54 : Polynomial Functions

Possible Answers:

Correct answer:

Explanation:

Example Question #55 : Polynomial Functions

Possible Answers:

Correct answer:

Explanation:

Example Question #51 : Polynomial Functions

Consider the polynomial

Which of the following is true of the rational zeroes of  ?

Hint: Think "Rational Zeroes Theorem".

Possible Answers:

 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.

Correct answer:

1 is the only rational zero.

Explanation:

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?

Possible Answers:

Correct answer:

Explanation:

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?

Possible Answers:

Correct answer:

Explanation:

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?

Possible Answers:

One or three

Exactly one

Exactly two

Exactly three

None or two

Correct answer:

None or two

Explanation:

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 ?

Possible Answers:

B

C

None of these graphs are correct.

Correct answer:
Explanation:

The function  shifts a function f(x) units to the left. Conversely,  shifts a function f(x) units to the right. In this question, we are translating the graph two units to the left.

To translate along the y-axis, we use the function  or .

Example Question #62 : Polynomial Functions

Which of the following graphs correctly represents the quadratic inequality below (solutions to the inequalities are shaded in blue)?

Possible Answers:

Incorrect1

Incorrect3

Correct

Incorrect4

Incorrect2

Correct answer:

Correct

Explanation:

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:

Graph of equation

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:

Correct

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