Square and Cube Roots Quiz Set 005

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Question 1

If $√2$ = 1.41, then what is the value of ${√2}/5$ − $13/{√2}$ + $√8$?

 A

-6.081.

 B

+6.081.

 C

-6.009.

 D

+6.009.

Soln.
Ans: a

The given expression can be simplified to ${{(√2)^2} - {5 × 13} + {5 × √2 × √{2 × 2^2}}}/{5 × √2}$, which is same as ${2 - 65 + 20}/{5 × √2}$, which is same as ${-43/{5 × √2}$. Rationalizing, we get ${-43/{5 × √2} × {√2/√2}$ which gives ${-43√2}/10$ which = -6.081.


Question 2

What is √0.0064?

 A

0.08.

 B

0.16.

 C

0.016.

 D

0.8.

Soln.
Ans: a

We can see that 0.08 × 0.08 = 0.0064, so square root is 0.08.


Question 3

What is √(9720) × √(30)?

 A

540.

 B

450.

 C

496.

 D

196.

Soln.
Ans: a

We can see that √(9720) × √(30) is same as √(2 × 2 × 2 × 3 × 3 × 3 × 3 × 3 × 5 ) × √(2 × 3 × 5 ) which equals √(24 × 36 × 52), which equals (22 × 33 × 51), which gives 540.


Question 4

What is cube root of 0.000343?

 A

0.07.

 B

.343

 C

0.007.

 D

0.700.

Soln.
Ans: a

We can see that 0.07 × 0.07 × 0.07 = 0.000343, so cube root is 0.07.


Question 5

If x = 0.8547, then what is the value of $4x + √{16x^2 - 8x + 1}$?

 A

1.

 B

16.

 C

2.

 D

4.

Soln.
Ans: a

By inspection, $4x + √{16x^2 - 8x + 1}$ is same as $4x + √{({1 - 4x})^2}$, which is same as 4x + (1 - 4x) = 1.


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Creative Commons License
This Blog Post/Article "Square and Cube Roots Quiz Set 005" 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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