HiSET: Math : Zeroes of polynomials

Study concepts, example questions & explanations for HiSET: Math

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Example Questions

Example Question #1 :Identification

The equation

has two distinct solutions. What is their sum?

Possible Answers:

Correct answer:

Explanation:

It is not necessary to actually find the solutions to a quadratic equation to determine the sum of its solutions.

First, get the equation in standard formby subtractingfrom both sides:

If a quadratic equation has two distinct solutions, which we are given here, their sum is the linear coefficient. In this problem,, makingthe correct choice.

Example Question #1 :Zeroes Of Polynomials

The graph of the polynomial function

has one and only one zero on the interval. On which subinterval is it located?

Possible Answers:

Correct answer:

Explanation:

The Intermediate Value Theorem (IVT) states that if the graph of a functionis continuous on an interval, andanddiffer in sign, thenhas a zero on. Consequently, the way to answer this question is to determine the signs ofon the endpoints of the subintervals -. We can do this by substituting each value foras follows:

assumes positive values forand negative values for. By the IVT,has a zero on.

Example Question #1 :使用0构造函数的一个粗略的图tion

The graph of a function is shown below, with labels on they-axis hidden.

Graph zeroes 2

Determine which of the following functions best fits the graph above.

Possible Answers:

Correct answer:

Explanation:

Use the zeroes of the graph to determine the matching function. Zeroes are values ofxwhere. In other words, they are points on the graph where the curve touches zero.

Visually, you can see that the curve crosses the x-axis when,, and. Therefore, you need to look for a function that will equal zero at thesexvalues.

A function with a factor ofwill equal zero when, because the factor ofwill equal zero. The matching factors for the other two zeroes,and, areand, respectively.

The answer choicehas all of these factors, but it is not the answer because it has an additional zero that would be visible on the graph. Notice it has a factor of, which results in a zero at. This additional zero that isn't present in the graph indicates that this cannot be matching function.

is the answer because it has all of the required factors and, as a result, the required zeroes, while not having additional zeroes. Notice that the constant coefficient of negative 2 does not affect where the zeroes are.

Example Question #1 :Zeroes Of Polynomials

Graph zeroes

Which of the functions below best matches the graphed function?

Possible Answers:

Correct answer:

Explanation:

First, look at the zeroes of the graph. Zeroes are where the function touches the x-axis (i.e. values ofwhere).

The graph shows the function touching the x-axis when,, and at a value in between 1.5 and 2.

Notice all of the possible answers are already factored. Therefore, look for one with a factor of(which will makewhen), a factor ofto makewhen, and a factor which will makewhenis at a value between 1.5 and 2.

This function fills the criteria; it has anand anfactor. Additionally, the third factor,, will result inwhen, which fits the image. It also does not have any extra zeroes that would contradict the graph.

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