Square and Cube Roots Quiz Set 008

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Question 1

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

 A

${-7√11}/66$.

 B

${+7√11}/66$.

 C

${-11√7}/66$.

 D

${-18√11}/66$.

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 2

What is the value of $x$ in $√{0.0064 × x}$ = 0.8?

 A

100.

 B

8.

 C

80.

 D

0.8.

Soln.
Ans: a

The given expression can be simplified to $0.0064 × x$ = $0.8^2$, which gives x = ${0.8^2}/0.0064$, which is same as $0.64/0.0064$ which gives 100.


Question 3

If x = 0.5356, then what is the value of $9x + √{4x^2 - 4x + 1}$?

 A

4.75.

 B

4.50.

 C

4.25.

 D

5.00

Soln.
Ans: a

By inspection, $9x + √{4x^2 - 4x + 1}$ is same as $9x + √{({1 - 2x})^2}$, which is same as 9x + (1 - 2x) = 1 + 7x = 4.75.


Question 4

If $4√3 + √27 = 12.12$, then what is the value of $√12 + 5√3$?

 A

12.12.

 B

12.00.

 C

11.12.

 D

12.96.

Soln.
Ans: a

The given expression can be rearranged like this: $4√3 + √{3^{2} × 3}$, which is same as $4√3 + 3√3$ which is same as $7√3 = 12.12$, from which we get $√3 = 1.73$. Next we can see that $√12 + 5√3$ is same as $√{2^{2} × 3} + 5√3$, which is same as $7√3$, which gives $7 × 1.73$ = 12.12.


Question 5

If $√2$ = 1.41, then what is the value of ${√2}/5$ − $9/{√2}$?

 A

-6.081.

 B

-3.042.

 C

+6.081.

 D

+3.042.

Soln.
Ans: a

The given expression can be simplified to ${{(√2)^2} - 5 × 9}/{5 × √2}$, which is same as ${2 - 45}/{5 × √2}$, which is same as ${-43/{5 × √2}$. Rationalizing, we get ${-43/{5 × √2} × {√2/√2}$ which gives ${-43√2}/10$ which = -6.081.


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Creative Commons License
This Blog Post/Article "Square and Cube Roots Quiz Set 008" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2019-08-18.

Posted by Parveen(Hoven),
Aptitude Trainer


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