Aptitude - Square Root and Cube Root - Discussion

Discussion :: Square Root and Cube Root - General Questions (Q.No.9)

9. 

The square root of (7 + 35) (7 - 35) is

[A]. 5
[B]. 2
[C]. 4
[D].

35

Answer: Option B

Explanation:

(7 + 35)(7 - 35) = (7)2 - (35)2  = 49 - 45  = 4  = 2.

Amu said: (Sep 6, 2011)  
(a+b)(a-b) = a^2-b^2

So ans must be 4 What is the necessity to take square root?

Please explain me.

Siri said: (Sep 7, 2011)  
Here square root is already there. so, a+b * a-b = a2-b2. so, square root a2-b2. so answer is 2 only

Jony Singla said: (Jun 7, 2013)  
No answer is 4 because they can't mention square root whole number, they are only mention the square root is root 5 not to 7 or 3.

Rohi said: (Feb 12, 2014)  
Just apply (a+b)(a-b) = (a^2-b^2) formula.

Manju said: (Jun 24, 2014)  
This question is in (a-b)(a+b) form. So we can simplify as a^2-b^2.

So, 7^2 - (9*5) = 49-45 = 4.

S.Ramu said: (Sep 6, 2014)  
Just applying the formula (a+b)*(a-b) = a^2-b ^2.

Keshav Kumar Mishra said: (Oct 7, 2014)  
The question is in the form of (a+b)(a-b) and
So that,
7*7 = 49.
49-45 = 4.

Rachana said: (Feb 11, 2015)  
Correct Answer is 2 (because question about square root not square) :).

Joe said: (Jul 12, 2015)  
Am confuse if (7)^2 = 49 then how possible (35)^2=45?

Selvi said: (May 26, 2016)  
As per my knowledge, the answer should be 4.

Pradhi said: (Jul 10, 2016)  
The answer should be 4 only. There is no whole square root is given in question.

Shilpa Sudhan said: (Aug 20, 2016)  
@Joe.

(3R5)^2 = 3 to the power 2 and root 5 to the power 2 root 5 to the power 2 can be written as root 5 into root 5 which is equal to 5 now we get 3^2 * 5 = 45.

Swathi said: (Oct 13, 2016)  
Please solve this question in the easy way of method.

Anil said: (Dec 17, 2016)  
3√3 * (4) how to solve this?

Please help me.

Vidya Channabasava Kabber said: (May 19, 2017)  
The answer should be 4. How it is 2. Can you explain?

Rafeeq said: (Jul 11, 2017)  
In the question, it is mentioned Square root of....

And the given no is (a+b)(a-b) form. After solving using this formula you will get 4 as the answer. Now note the question, it is mentioned as the square root of. Hence we have to take the whole square root. Hope my answer will be understood by everyone.

Sreekanth said: (Aug 5, 2017)  
Here square root is already there.
So, a+b * a-b = a2-b2. so, square root a2-b2. So answer is 2 only.

Priya said: (Dec 7, 2018)  
@All.

It is mentioned that the square root of (find the square root of a given item), by solving we will get 4. Take the square root of 4 the answer is 2.

Sonam said: (Mar 11, 2019)  
Sir, how come 45? please tell me.

Sweety said: (Aug 26, 2019)  
How come 45?

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