Tag: maths

Questions Related to maths

Let p and q be any two logical statements and $r : p \rightarrow (\sim p \vee q)$. If r has a truth value F, then the truth values of p and q are respectively

  1. F, F

  2. T, T

  3. F, T

  4. T, F


Correct Option: D
Explanation:
p q $\sim$p $\sim$ p $\vee$ q r
T T F T T
F F T T T
T F F F F
F T T T T

$\therefore$ Clearly from above able, If r has a truth value F, then the truth values of p and core T and F respectively.

State, whether the is given the statement, is True or False.
$\sim [(p \vee \sim q) \rightarrow (p \wedge \sim q)] \equiv (p \vee \sim q) \wedge (\sim \vee q)$

  1. True

  2. False


Correct Option: A
Explanation:
 $p$  $q$  $\sim q$  $(p\vee \sim q)$  $(p\wedge \sim q)$ $(p\vee \sim q)\rightarrow (p\wedge \sim q)$  $\sim[(p\vee \sim q)\rightarrow (p\wedge \sim q)]$
 $T$  $T$  $F$  $T$  $F$  $F$  $T$
 $T$  $F$  $T$  $T$  $T$  $T$   $F$
 $F$  $T$  $F$  $F$  $F$  $T$   $F$
 $F$  $F$  $T$  $T$  $F$  $F$ $T$
 $p$  $q$  $\sim q$  $(p\vee \sim q)$ $\sim p$  $(\sim p \vee q)$ $(p\vee \sim q)\wedge (\sim p \vee q)$
 $T$  $T$  $F$  $T$  $F$  $T$  $T$
 $T$  $F$  $T$  $T$  $F$  $F$  $F$
 $F$  $T$  $F$   $F$  $T$  $T$  $F$
 $F$  $F$  $T$  $T$  $T$  $T$  $T$

$\sim (p \vee q) \vee (\sim p \wedge q) \equiv ?$

  1. $\sim q$

  2. $q$

  3. $\sim p$

  4. $p$


Correct Option: C
Explanation:

$\sim (p\vee q)\vee (\sim p \wedge q)$
$=(\sim p \wedge \sim q) \vee (\sim p \wedge q)$ De'Morgan Law
$=(\sim p)\wedge (\sim q\vee q)$ Distributive Law
$=(\sim p)\wedge T$ Negation Law
$=\sim p$ Identity law

State whether the following statements is True or False?
$p \leftrightarrow q \equiv (p \wedge q) \vee (\sim p \wedge \sim q)$

  1. True

  2. False


Correct Option: A
Explanation:
given statement 
$p\leftrightarrow q=(p\wedge q)\vee (\sim p\wedge \sim q)$
taking RHS
$(p\wedge q)\vee (\sim p\wedge \sim q)$
$(p\wedge q)\vee (\sim(p\wedge  q))$
$(p\wedge q)\wedge(p\wedge  q)$
$p\leftrightarrow q$
It is true

Let p,q be statements. Negation of statement $p \leftrightarrow  ~ q$, is

  1. $~ q \rightarrow p$

  2. $ ~ p v q$

  3. $p \leftrightarrow q$

  4. $p \rightarrow q$


Correct Option: A
Explanation:
p q ~q $p \leftrightarrow ~q$ $~(p \leftrightarrow ~q)$ $~q \rightarrow p$ $~p v q$ $p \leftrightarrow q$ $p \rightarrow q$
T T F F T T T T T
T F T T F T F F F
F T T T F T T F T
F F F F T F T T T

Which point on the number line most likely represent $-2\cfrac { 5 }{ 8 } $?

  1. On the left of $-3$

  2. On the right of $-2$

  3. Between $-2$ and $-3$

  4. In the middle of $-2$ and $-3$


Correct Option: C
Explanation:
$-2\cfrac { 5 }{ 8 } $

$-2\cfrac { 5 }{ 8 } =(-1)2\cfrac { 5 }{ 8 } $

$=-1\times \cfrac { 21 }{ 8 } $

$=-2.625$

It lies in between $-3$ and $-2$

$A,B,C$ and $D$ are all different digits between $0$ and $9$. If $AB+DC=7B\ (AB,DC$ and $7B$ are two digit numbers), then the value of $C$ is

  1. $0$

  2. $1$

  3. $2$

  4. $3$

  5. $5$


Correct Option: A

If $\sqrt{a}$ is an irrational number, what is a? 

  1. Rational

  2. Irrational

  3. $0$

  4. Real


Correct Option: A
Explanation:

Consider the given irrational number$\sqrt{a}$ ,

Definition  of rational number- which number can be write in the form of $\dfrac{p}{q}$ but $q\ne 0$ is called rational number.

Hence, $a=\dfrac{a}{1}$

That why  $a$ is rational number

 

Hence, this is the answer.

Which of the following is irrational

  1. $\sqrt {\dfrac{4}{9}} $

  2. $\dfrac{4}{5}$

  3. $\sqrt 7 $

  4. $\sqrt {81} $


Correct Option: C
Explanation:
A $=\sqrt{\dfrac{4}{9}}=\dfrac{2}{3}$         Rational

B $=\dfrac{4}{5}$                       Rational

C $=\sqrt7$                     Irrational

D $=\sqrt{81}=9$          Rational

The number $23+\sqrt{7}$ is

  1. Natural number

  2. Irrational number

  3. Rational number

  4. None of these


Correct Option: B
Explanation:

As we've $\sqrt{7}$ is an irrational number and $23$ is a rational number then the sum of an irrational number and a rational number is again an irrational number.