Tag: set language

Questions Related to set language

Which of the following sets is not a finite set ?

  1. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in R} $

  2. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in Z} $

  3. ${ (x,y):{ x }^{ 2 }\le y\le |x|,\ \ x,y\in Z} $

  4. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }=1,\ \ x,y\in Z} $


Correct Option: A
Explanation:

The set ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in R} $ consists of all the points in the first quadrant which lie inside the circle ${ x }^{ 2 }+{ y }^{ 2 }=1$ and above the line $x+y=1$ .So, it is not a finite set.
Option $A$ is correct.

Which of the following is incorrect.

  1. The power set of an infinite set is infinite.

  2. The union of two infinite set is infinite.

  3. The intersection of two infinite set is infinite.

  4. The cardinality of an infinite set is infinite.


Correct Option: C
Explanation:

The intersection of an infinite set may be finite.
Example:
$A={x:x\in N; x>2}$
$B={x:x\in I; x<5}$
Here, Both $A$ and $B$ are infinite but its intersection are finite.

Define infinite set .
Is ${x:x\in R:1\le x\le 3}$ a infinite set?

  1. True

  2. False


Correct Option: A
Explanation:

Definition: A set having infinite number of elements is known as infinite set.
 ${x:x\in R:1\le x\le 3}$ is a infinite set because since $x\in R$, there are infinte number of real numbers lie in between two numbers.

Choose that set of numbers from the option set that is similar to the given set {10,15,65}

  1. ${10, 6, 5}$

  2. ${124, 5, 3}$

  3. ${95, 25, 5}$

  4. ${168, 15, 4}$


Correct Option: C
Explanation:

option C 

since in both the given set all the elements are divisible y 5 

Let S be the set of all values of x such that $log _{2x}(x^{2}+5x+6)<1$ then the sum of all integral value of x in the set S, is

  1. 0

  2. 8

  3. 9

  4. 10


Correct Option: A
Explanation:
$ log _{2x}(x^{2}+5x+6)< 1 $

$ \Rightarrow x^{2}+5x+6< 2x^1 $

$ \Rightarrow x^{2}+3x+6< 0 $

But $ x^{2}+3x+6 = 0 $ has no real roots 

$ \therefore S$  is an empty set 

$ \therefore $ sum of all integral values of $ x = 0 $ 

If a set contains $n$ elements then number of elements in its power set is

  1. $2^n-n$

  2. $2^n-2$

  3. $2^n$

  4. $n^2$


Correct Option: C
Explanation:

Given the set contains $n$ elements.

Then its power set will contains $2^n$ elements.

If $A,B$ are two non-empty sets which of the following statement is false

  1. $A-B=A\cap \left( { B }^{ C } \right) $

  2. $A-B=A\cap \left( { A\cap B } \right) $

  3. $A-B=A-\left( { B }^{ C } \right) $

  4. $A-B=\left( { A\cup B } \right) -B$


Correct Option: C

If $A=\left{1, 2, 3\right}$, then the numbers of subsets of set $A$ containing element $3$, is 

  1. $24$

  2. $28$

  3. $8$

  4. $16$


Correct Option: C
Explanation:
The set $\left\{1, 2, 3\right\}$ has $8$ subsets. The first subset would be the null or empty subset, which contains none of the numbers: $\left\{\right\}$.
 The null set is a subset of every set. The other subsets would include some of the numbers in the set, but not all of them: $\left\{1\right\}$,$\left\{2\right\}$,$\left\{3\right\}$,$\left\{1,2\right\}$,$\left\{1,3\right\}$,$\left\{2,3\right\},\{1,2,3\}$

Let ${ a } _{ 1 },{ a } _{ 2 },{ a } _{ 3 },............{ a } _{ 10 }$ be in G.P. with ${ a } _{ i }>0$ for $i=1,2,....,10$ and $S$ be the set of pairs $(r,k),r\quad k\in N$ ( the set of natural numbers) for which
$\left| { log } _{ e }{ a } _{ 1 }^{ r }{ a } _{ 2 }^{ k }\quad { log } _{ e }{ a } _{ 2 }^{ r }{ a } _{ 3 }^{ k }\quad { log } _{ e }{ a } _{ 3 }^{ r }{ a } _{ 4 }^{ k }\ { log } _{ e }{ a } _{ 4 }^{ r }{ a } _{ 5 }^{ k }\quad { log } _{ e }{ a } _{ 5 }^{ r }{ a } _{ 6 }^{ k }\quad { log } _{ e }{ a } _{ 6 }^{ r }{ a } _{ 7 }^{ k }\ { log } _{ e }{ a } _{ 7 }^{ r }a _{ 8 }^{ k }\quad { log } _{ e }{ a } _{ 8 }^{ r }{ a } _{ 9 }^{ k }\quad { log } _{ e }{ a } _{ 9 }^{ r }{ a } _{ 10 }^{ k } \right| =0$
Then the number of elements in S, is :

  1. Infinitely many

  2. 4

  3. 10

  4. 2


Correct Option: A

Classify $A = {x | x$ is a multiple of $3}$ as 'finite' or 'infinite'.

  1. Finite

  2. Infinite

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

A will be an infinite set as we have many multiples of 3 such has 3, 6, 9, 12 and so on