# Square and Cube Roots Quiz Set 005

### 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. 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 2020-02-07. Published on: 2016-04-20