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Example Questions
Example Question #31 : Irrational Numbers
Which of the following is an irrational number?
An irrational number is a number that cannot be rewritten as a ratio of two numbers such as or
since their decimal numbers are continuous.
Square roots that are not perfect squares are irrational such as:
Be careful with numbers that are fixed. Fixed numbers are finite and can be rewritten as a fractional term.
Imaginary numbers are neither irrational or real numbers and is defined as the term . The value of
is an imaginary number. These are called complex numbers.
Percentages can be rewritten as a fraction.
The answer is:
Example Question #71 : Number Theory
Try without a calculator.
True or false: the set
comprises only irrational numbers.
False
True
False
The square root of an integer is rational if and only if the integer is a perfect square of another integer.
,
so 16 is a perfect square, and is a rational number. The statement is therefore false.
Example Question #72 : Number Theory
Try without a calculator.
True or false: the set
comprises only irrational numbers.
True
False
True
is an irrational number, as is any integer multiple of
. All of the elements are integer multiples of
, so all of them are irrational.
Example Question #73 : Number Theory
Try without a calculator.
True or false: the set
comprises only irrational numbers.
False
True
True
is an irrational number, as is any integer multiple of
. All of the elements are integer multiples of
, so all of them are irrational.
Example Question #5129 : Algebra Ii
Which of the following represents an irrational number?
None of the numbers is irrational.
First, recall the definition of irrational numbers. Irrational numbers cannot be expressed as a ratio of integers.
The answer is incorrect because it is a repeating decimal that can be rewritten as the following fraction:
In a similar vein, the following choice is already written as a simple fraction (negative numbers are not irrational):
It is important to note that not all square roots are irrational. For instance, the following square root can be simplified quite easily:
The only answer that cannot be expressed as a simple fraction is:
The answer is:
Example Question #6 : Irrational Numbers
Which of the following is an irrational number?
A rational number can be expressed as a fraction of integers, while an irrational number cannot.
can be written as
.
is simply
, which is a rational number.
The number can be rewritten as a fraction of whole numbers,
, which makes it a rational number.
is also a rational number because it is a ratio of whole numbers.
The number, , on the other hand, is irrational, since it has an irregular sequence of numbers (
...) that cannot be written as a fraction.
Example Question #1 : Number Sets
If ,
, and
, then find the following set:
The union is the set that contains all the numbers from and
. Therefore the union is
.
Example Question #1 : Number Sets
If ,
, and
, find the following set:
The intersection is the set that contains only the numbers found in all three sets. Therefore the intersection is .
Example Question #2 : Number Sets
If ,
, and
, find the following set:
The intersection is the set that contains the numbers that appear in both and
. Therefore the intersection is
.
Example Question #3 : Number Sets
If ,
, and
, find the following set:
The intersection is the set that contains the numbers found in both sets. Therefore the intersection is .
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