Tag: irrational numbers

Questions Related to irrational numbers

There can be a pair of irrational numbers whose sum is irrational 

Such as: $\displaystyle \sqrt{3}+2$ and $\displaystyle 5+\sqrt{2}$

  1. True

  2. False


Correct Option: A
Explanation:

To get the sum as irrational, the numbers need to have an irrational part as well which are different from each other.

Example, the pair of numbers $ \sqrt{3} + 2 $ and $ 5 + \sqrt {2} $ have the sum $ \sqrt{3} + 2 + 5 + \sqrt {2} = 7 + \sqrt {2} + \sqrt {3} $ which is an irrational number too.

State true or false:

$\sqrt3$ is an irrational number

  1. True

  2. False


Correct Option: A
Explanation:

Decimal form of $\sqrt { 3 } $ is non terminating and non repeating, So, it is irrational number.

Simplify : 

$\displaystyle \sqrt{2}\times \sqrt[3]{3} \times \sqrt[4]{4}$.

  1. $\sqrt[3]{12}$

  2. $\sqrt[3]{24}$

  3. $\sqrt[3]{20}$

  4. $\sqrt[3]{25}$


Correct Option: B
Explanation:

$ \sqrt{2} \times \sqrt[3] {3} \times \sqrt[4]{4}$
$=2^{ \frac { 1 }{ 2 }  } \times 3^{ \frac { 1 }{ 3 }  }\times 2^{ \frac { 2 }{ 4 }  }$
$=2^{ \frac { 1 }{ 2 }  } \times 2^{ \frac { 1 }{ 2 }  }\times 3^{ \frac { 1 }{ 3 }  }$
$=2  \times3^{ \frac { 1 }{ 3 }  }$
$=2^{ \frac { 3 }{ 3 }  }\times3^{ \frac { 1 }{ 3 }  }  $
$=\sqrt [ 3 ]{ 2^{ 3 } }\times\sqrt[3]{3}$
$=\sqrt[3]{8\times3}$
$=\sqrt[3]{24}$

The value of  $\displaystyle \pi $ upto $50$ decimal places is $:\:314159265358979323846264338327950288419716939937510$
Which are the least occurring digits?
  1. $0$

  2. $1$

  3. $2$

  4. $3$


Correct Option: A
Explanation:

We will be considering the digits only after the decimal point.


Digit after decimal point frequency
0 2
1 5
2 5
3 8
4 4
5 5
6 4
7 4
8 5
9 8
Total 50

The maximum occurring digits are 3 and 9. 
The least occurring digit is 0.

Which of the following is irrational?

  1. $\dfrac {22}{7}$

  2. $3.141592$

  3. $2.78181818$

  4. $0.123223222322223.......$


Correct Option: D
Explanation:

An irrational number is any real number that cannot be expressed as a ratio of integers. Irrational numbers are those real numbers that cannot be represented as terminating or repeating decimals.
Among all the options only $(D)$ $0.123223222322223$...... is non terminating and non repeating decimal.Therefore, it is a irrational number.

$\sqrt 7$ is

  1. A rational number

  2. An irrational number

  3. Not a real number

  4. Terminating decimal


Correct Option: B
Explanation:

Rational numbers are those numbers which can be expressed in the form $ \dfrac {p}{q} $, where p and q are integers and $ q \neq 0 $
Numbers which are not rational numbers are called irrational numbers.
Since, $ \sqrt {7} $ cannot be written in
$ \dfrac {p}{q} $, where $p$ and $q$ are integers and $ q \neq 0 $; it is an irrational number.

State whether the following statement are true or false? Justify your answers.

Every irrational number is a real number.

  1. True

  2. False


Correct Option: A
Explanation:

Real number consists of collection of rationals and irrationals.

Hence, every irrational number is also a real number.

Example-2 is also real.

State whether the following statement are true or false? Justify your answers.

Every real number is an irrational number.

  1. True

  2. False


Correct Option: B
Explanation:

The statement is false since real numbers consists of both rational and irrational numbers. $5,65,8/9...$ are all real numbers which are rational.

Classify the following numbers as rational or irrational : $2-\sqrt{5}$

  1. Irrational number

  2. Rational number

  3. Less Data

  4. None of the above


Correct Option: A
Explanation:

$2$ is rational

$\sqrt 5 =2.035.........$ which is non terminating and non repeating hence irrational number.
We know that rational- irrational= irrational number.
Hence $2-\sqrt 5= irrational \,  number$
Hence, option A is the correct answer.

Decimal representation of an irrational number is always

  1. Terminating

  2. Terminating, Repeating

  3. Non-Terminating, Repeating

  4. Non-Terminating, Non-Repeating


Correct Option: D
Explanation:

Decimal representation of an irrational number is always non terminating non repeating.

 For example,$\sqrt{2}$ $=1.41421356237309504880168872420969807856967187537694807317667973799...$