Number Theory

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Questions 1 - 10
1

Which of the following numbers are irrational?

Explanation

The definition of irrational numbers is that they are real numbers that cannot be expressed in a common ratio or fraction.

The term is imaginary which equals to .

The other answers can either be simplified or can be written in fractions.

The only possible answer shown is .

2

Which of the following is an irrational number?

Explanation

An irrational number is any number that cannot be written as a fraction of whole numbers. The number pi and square roots of non-perfect squares are examples of irrational numbers.

can be written as the fraction . The term is a whole number. The square root of is , also a rational number. , however, is not a perfect square, and its square root, therefore, is irrational.

3

Which of the following is an irrational number?

Explanation

An irrational number is any number that can not be expressed as a ratio of integers, i.e. a fraction. Therefore, the only irrational number listed is .

4

Which line plot corresponds to the inequality below?

Question_1_correct

Question_1_incorrect_1

Question_1_incorrect_2

Question_1_incorrect_3

Explanation

A closed circle indicates "greater than or equal to" or "less than or equal to," while and open circle indicates "greater than" or "less than". We can tell from the inequality that our line plot will only have closed circles, as the only symbol is "greater than or equal to."

Subtract from both sides.

Divide both sides by .

Our plot will show a closed circle on , and extend infinitvely in the positive direction.

5

Which of the following is an irrational number?

Explanation

An irrational number is any number that cannot be written as a fraction of whole numbers. The number pi and square roots of non-perfect squares are examples of irrational numbers.

can be written as the fraction . The term is a whole number. The square root of is , also a rational number. , however, is not a perfect square, and its square root, therefore, is irrational.

6

Simplify the radical.

Cannot be simplified further.

Explanation

Find the factors of 128 to simplify the term.

We can rewrite the expression as the square roots of these factors.

Simplify.

7

Which of the following numbers are irrational?

Explanation

The definition of irrational numbers is that they are real numbers that cannot be expressed in a common ratio or fraction.

The term is imaginary which equals to .

The other answers can either be simplified or can be written in fractions.

The only possible answer shown is .

8

A plane flies at a rate of 210mi/h. If the plane has flown for five hours, how many miles has it traveled?

1050mi

42mi

215mi

840mi

1000mi

Explanation

Multiply the rate of travel (210 mi/hr) by the time traveled (5 hours), and you get the total distance, 1050 miles.

distance = rate * time

distance = (210mi/hr)(5hr)

distance = 1050mi

9

Which of the following is considered an irrational number?

Explanation

The irrational numbers do not have a representation of a ratio between two numbers. They cannot be expressed by a fraction.

Repeating decimal numbers are not irrational because they can be rewritten as a fraction.

For instance:

The number may represent the short version of , but is not irrational, because is a fixed number and be rewritten as a ratio between two numbers.

The answer is:

10

Which of the following is considered an irrational number?

Explanation

The irrational numbers do not have a representation of a ratio between two numbers. They cannot be expressed by a fraction.

Repeating decimal numbers are not irrational because they can be rewritten as a fraction.

For instance:

The number may represent the short version of , but is not irrational, because is a fixed number and be rewritten as a ratio between two numbers.

The answer is:

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