Square and Cube Roots Quiz Set 006

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Question 1

What is the value of $(√8 - 1/√8)^2$?

 A

$6{1/8}$.

 B

$6{1/4}$.

 C

$6{3/4}$.

 D

$6{1/3}$.

Soln.
Ans: a

I will give a general solution for any n. $(√n - 1/√n)^2$ is same as $({(√n)^2 - 1}/√n)^2$ which becomes $(n - 1)^2/n$. Putting n = 8, we get ${49/8}$, which is same as: $6{1/8}$.


Question 2

What is the value of $x$ in $√{0.0025 × x}$ = 0.5?

 A

100.

 B

10.

 C

1000.

 D

10000.

Soln.
Ans: a

The given expression can be simplified to $0.0025 × x$ = $0.5^2$, which gives x = ${0.5^2}/0.0025$, which is same as $0.25/0.0025$ which gives 100.


Question 3

What is √(4320) × √(4320)?

 A

4320.

 B

4400.

 C

4416.

 D

4520.

Soln.
Ans: a

We can see that √(4320) × √(4320) is same as √(2 × 2 × 2 × 2 × 2 × 3 × 3 × 3 × 5 ) × √(2 × 2 × 2 × 2 × 2 × 3 × 3 × 3 × 5 ) which equals √(210 × 36 × 52), which equals (25 × 33 × 51), which gives 4320.


Question 4

What is the value of ${√11}/6$ − $3/{√11}$?

 A

${-7√11}/66$.

 B

${+7√11}/66$.

 C

${-3√11}/66$.

 D

${+3√11}/66$.

Soln.
Ans: a

The given expression can be simplified to ${{(√11)^2} - 6 × 3}/{6 × √11}$, which is same as ${11 - 18}/{6 × √11}$, which is same as ${-7/{6 × √11}$. Rationalizing, we get ${-7/{6 × √11} × {√11/√11}$ which gives ${-7√11}/66$


Question 5

What is the value of $√{7 + √1764}$?

 A

7.

 B

8.

 C

14.

 D

6.

Soln.
Ans: a

The given expression is same as $√{7 + √42^2}$, which becomes $√{7 + 42}$, or $√49$ which gives 7 as the answer. Please note that squares of as many numbers should be always on your tips.


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This Blog Post/Article "Square and Cube Roots Quiz Set 006" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-06-24.

Posted by Parveen(Hoven),
Aptitude Trainer


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