Tag: maths

Questions Related to maths

From which odd number you will get the value zero, for the square root of the number 64 using repeated subtracting method?

  1. 13

  2. 15

  3. 9

  4. 5


Correct Option: B
Explanation:

Repeated subtraction method: Subtract successive odd numbers from the given number starting from 1 till the difference becomes zero.
So, 64 - 1 = 63
63 - 3 = 60
60 - 5 = 55
55 - 7 = 48
48 - 9 = 39
39 - 11 = 28
28 - 13 = 15
15 - 15 = 0.
15 is the odd number, we get the value of zero for the square root of the number 64.

Calculate the value of $\sqrt{\frac{144}{256}}$.

  1. 0.55

  2. 0.75

  3. 0.65

  4. 0.45


Correct Option: B
Explanation:

$\sqrt{\dfrac{144}{256}}$
= $\dfrac{12}{16}$.
= 0.75

Find the square root of 1369.

  1. 31

  2. 33

  3. 36

  4. 37


Correct Option: D
Explanation:

$\sqrt{1369}= \sqrt{37 \times 37}$
So, the square root of 1369 is 37.

Subtracting which odd number will get the value of 144 for the square root of the number 169 using repeated subtraction method?

  1. 3

  2. 5

  3. 7

  4. 9


Correct Option: D
Explanation:

Repeated subtraction method: Subtract successive odd numbers from the given number starting from 1 till the difference becomes zero.
So, 169 - 1 = 168
168 - 3 = 165
165 - 5 = 160
160 - 7 = 153
153 - 9 = 144
9 is the odd number, subtracting with 153 to get the value of 144.

Evaluate: $\sqrt{\frac{784}{196}}$

  1. 5

  2. 4

  3. 3

  4. 2


Correct Option: D
Explanation:

$\sqrt{\dfrac{784}{196}}$
= $\dfrac{28}{14} = 2$.

If $x=5+2\sqrt { 6 } $, then $\sqrt{ x }+\dfrac{1}{\sqrt { x }} $ is ?

  1. $2\sqrt{ 2 } $

  2. $2\sqrt { 3 } $

  3. $\sqrt { 3 } +\sqrt { 2 } $

  4. $\sqrt { 3 } -\sqrt { 2 } $


Correct Option: A
Explanation:

Let $A=\sqrt { x } +\cfrac { 1 }{ \sqrt { x }  } $
$\Rightarrow { A }^{ 2 }=x+\cfrac { 1 }{ x } -2=\left( 5+2\sqrt { 6 }  \right) +\cfrac { 1 }{ 5+2\sqrt { 6 }  } -2$
$=5+2\sqrt { 6 } +\cfrac { 5-2\sqrt { 6 }  }{ 25-24 } -2=8$ $\text{[Rationalising the denominator]}$
$=5+2\sqrt { 6 } + { 5-2\sqrt { 6 }  } -2=8$
$ \Rightarrow A^2=8 $
$ \Rightarrow A=2\sqrt { 2 } $

If $a,b,c$ are three distinct positive real numbers then the number of real roots of $ax^2+2b|x|-c=0$ is

  1. $0$

  2. $2$

  3. $4$

  4. none of these


Correct Option: B
Explanation:

${ ax }^{ 2 }+2b{ |x| }-c=a{ |x| }^{ 2 }+2b|x|-c$

                       $|x| =\dfrac { -b\pm \sqrt { 4{ b }^{ 2 }+4ac }  }{ 2a }$
                             $=\dfrac { -2b\pm 2\sqrt { { b }^{ 2 }+ac }  }{ 2a }$
                             $=\dfrac { -b\pm \sqrt { { b }^{ 2 }+ac }  }{ a }$
                             $=\dfrac { -b+\sqrt { { b }^{ 2 }+ac }  }{ a }$ (|x| can't be negative)
$\therefore 2$ real roots                            

A group of people decided to collect as many rupees from each member of the group as is the number of members. If the total collection amounts to $2209$, what is the number of members in the group?

  1. $37$

  2. $47$

  3. $107$

  4. $43$


Correct Option: B
Explanation:

Rupee collected from each member $=$ number of member in group $=$ $k$

$k\times k$ $=$ $2209$
$k=$ $\sqrt{2209}$
$k=$ $47$
Hence, Option B is correct.

For what value of $\displaystyle x+\frac { 1 }{ 4 } \sqrt { x } +{ a }^{ 2 }$ will be perfect square -

  1. $\displaystyle \pm { 1 }/{ 18 }$

  2. $\displaystyle \pm { 1 }/{ 8 }$

  3. $\displaystyle \pm { 1 }/{ 5 }$

  4. $\displaystyle { 1 }/4$


Correct Option: B
Explanation:

If $\displaystyle x+\frac { 1 }{ 4 } \sqrt { x } +{ a }^{ 2 }$ is a perfect square
then $\displaystyle \frac { 1 }{ 4 } \sqrt { x } =2\times \sqrt { x } \times \left( \pm a \right) $
$\displaystyle \therefore \quad a=\pm \frac { 1 }{ 8 } $

Solve:
$ \sqrt { 225 } -x=0 ,x=?$
  1. $10$

  2. $4$

  3. $15$

  4. $5$


Correct Option: C
Explanation:
$\sqrt { 225 } =15$
$\sqrt { 225 } -x=0$
$15-x=0$
$x=15$