# Square and Cube Roots Quiz Set 001

### Question 1

One-fifth of the square-root of which number is 0.6?

A

9.

B

16.

C

4.

D

25.

Soln.
Ans: a

Let the number be n. So \${1/5} × √n\$ = 0.6, which gives \$√n\$ = 5 × 0.6 = 3. so n = \$3^2\$ = 9.

### Question 2

If x = 0.7727, then what is the value of \$4x + √{16x^2 - 8x + 1}\$?

A

1.

B

8.

C

16.

D

9.

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.

### Question 3

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.

### 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

What is the value of \$√{3 + √1089}\$?

A

6.

B

3.

C

12.

D

9.

Soln.
Ans: a

The given expression is same as \$√{3 + √33^2}\$, which becomes \$√{3 + 33}\$, or \$√36\$ which gives 6 as the answer. Please note that squares of as many numbers should be always on your tips.