Aptitude - Numbers - Discussion

Discussion :: Numbers - General Questions (Q.No.138)

138. 

{(476 + 424)2 - 4 x 476 x 424} = ?

[A]. 2906
[B]. 3116
[C]. 2704
[D]. 2904
[E]. None of these

Answer: Option C

Explanation:

Given Exp. = [(a + b)2 - 4ab], where a = 476 and b = 424
= [(476 + 424)2 - 4 x 476 x 424]
= [(900)2 - 807296]
= 810000 - 807296
= 2704.

Shahid said: (May 20, 2011)  
[(a + b)2 - 4ab]=[(a-b)^2]

From the above we have a=476 ,b=424
so Result is (476-424)^2
=52^2=2704

Arif said: (Sep 12, 2011)  
[(a+b)^2-4ab]=a^2+b^2+2ab-4ab
=(a-b)^2
=(476-424)^2
=52^2
=2704

Siva said: (Aug 18, 2014)  
[(a+b)^2-4ab] = a^2+b^2+2ab-4ab.
= (a-b)^2.
= (476-424)^2.
= 52^2.
= 2704.

Ipsita said: (Feb 1, 2016)  
But as we know:

(a-b)^2 = a^2-2ab+b^2.

Bindu said: (May 19, 2016)  
This is in the form of (a + b)^2 - 4ab.
So, (a^2 + b^2 + 2ab - 4ab).
= a^2 + b^2 - 2ab.
= (a - b)^2.

So, a = 476, b = 424 by substituting the value we get the answer.
= 2704.

Pritam said: (Mar 14, 2017)  
Nice and easy method @Bindu.

Krishna said: (Aug 17, 2018)  
4ab=(a+b)^2-(a-b)^2.
Thus (a+b) ^2-4ab=(a-b)^2..
a-b=476-424=52.
52^2=2704 =>answer.

Suraj said: (Sep 12, 2018)  
Sum of two numbers is twice their difference. If one of the number is 10then the other no is?

Please, anyone, answer this.

Swar said: (Dec 12, 2018)  
@Suraj.

Let two numbers be considered as x and y
As per question ,x+y=2(x-y) ,
Given one numbers as 10,
10+y=2(10-y),
10+y=20-2y,
2y+y=20-10,
3y=10,
Y=10/3.
Correct me, if I am wrong.

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