Tag: powers and roots

Questions Related to powers and roots

Find the value of each of the following, using the column method.
$(23)^2$
$(52)^2$

  1. 549, 2724

  2. 549, 2704

  3. 529, 2724

  4. 529, 2704


Correct Option: D
Explanation:

$(23)^2$
$a=2, b=3$

$i$ $ii$ $iii$
$a^2$ $2ab$ $b^2$
$4$$1$           $\underline { 5 }$ $12$$+0$           $1\underline { 2 }$ $\underline { 9 }$

$\therefore (23)^2=529$

$(52)^2$
$a=5, b=2$

$i$ $ii$ $iii$
$a^2$ $2ab$ $b^2$
$25$$+2$          $\underline { 27 }$ $20$$+0$          $2\underline { 0 }$ $\underline { 4 }$

$\therefore (52)^2=2704$

$144$ is the square of 

  1. $12$

  2. $11$

  3. $10$

  4. None of these


Correct Option: A
Explanation:

$12 \times 12 =144, 12^2 = 144$. 

$144$ is a square of number $12$.

Therefore, option A is the correct answer.

Square of $51$ is _______.

  1. 2601

  2. 1062

  3. 6201

  4. 1026


Correct Option: A
Explanation:

Squaring means multiplying a number with the same number.
Therefore, square of $51$ is $51 \times 51 = 2601$
Therefore, A  is the correct answer. 

Find the number whose square root is twice of its cubic root.

  1. $128$

  2. $64$

  3. $16$

  4. $4$


Correct Option: B
Explanation:

Let the number be $x.$
As per the problem $\sqrt {x}=2\times \sqrt [ 3 ]{x  } $
Raising both sides by $6$ times
$=(x^{1/2})^6 = 2^6(x^{1/3})^6$
$= x^{1/2\times 6} = 2^6 x^{1/3\times 6}$
or $ x^3 = 64 x^2$
or $x=64$

The unit digit of the square of the number $78$ is 

  1. $8$

  2. $2$

  3. $4$

  4. $6$


Correct Option: C
Explanation:

The square of the number $78$ is $6084$


Therefore, the unit digit of $6084$ is $4$

Solve:$(23.1)^2+(48.6)^2-(39.8)^2$

  1. $(36.21)^2$

  2. $\sqrt{12.8}$

  3. $163.84$

  4. $12.8$

  5. None of these


Correct Option: A
Explanation:

$Using\quad approximate\quad values,\quad we\quad will\quad calculate\quad the\quad values\quad the\quad given\quad problem\ \quad \quad =\quad { \left( 23.1 \right)  }^{ 2 }+{ \left( 48.6 \right)  }^{ 2 }-{ \left( 39.8 \right)  }^{ 2 }\ \quad \quad =\quad 533.61+2362.96-1584.04\ \quad \quad =\quad 1311.53\ \quad \quad =\quad approx...\quad { \left( 36.21 \right)  }^{ 2 }$

Non-perfect square numbers between square of $21$ and $22$

  1. 42

  2. 44

  3. 441

  4. 404


Correct Option: A
Explanation:

we know 

$(21)^2=441$
$(22)^2=484$
Number of non perfect square between $441$ and $484$
$=(484-441)-1=43-1$
$=42$

Write the $(T)$ of false $(F)$ for the following statements.
The product of two square number is a square number.

  1. True

  2. False


Correct Option: A
Explanation:

Take two numbers $3$ and $4$.

$\Rightarrow$  $3^2=9$ and $4^2=16$
$\Rightarrow$  Product of squares of $3$ and $4$ $=9\times 16=144$
We know, that $144$ is a square if $12$.
$\therefore$  The given statement " The product of two squares number is a square number " is true.

Find the square of the number $17$.

  1. $298$

  2. $289$

  3. $249$

  4. None of the above.


Correct Option: B
Explanation:

Square of a number means multiplying a number with the same number.

Square of $17\times 17 =289$.

Therefore, option B is the correct answer.

Give the square of number $22$.

  1. $212$

  2. $222$

  3. $484$

  4. $844$


Correct Option: C
Explanation:

Square of  a number means multiply a number with the same number.

$22 \times 22= 22^2  = 484$

Thus the square of number $22$ is $484$.

Therefore, option C is the correct answer.