Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 138)
138.
{(476 + 424)2 - 4 x 476 x 424} = ?
2906
3116
2704
2904
None of these
Answer: Option
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.
Discussion:
10 comments Page 1 of 1.

G Ajay Kumar said:   2 years ago
(a + b)^2 - 4ab = a^2 + b^2 + 2ab -4ab.
= a^2 + b^2 - 2ab,
= (a - b)^2.
therefore, the above equation can be written as,
= {(476 + 424)^2 - 4 x 476 x 424}.
= ( 476^2 + 424^2 - 2 x 476 x 424),
= (476 - 424)^2,
= 52^2,
= 2704.
(8)

Swar said:   7 years ago
@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.
(1)

Suraj said:   7 years ago
Sum of two numbers is twice their difference. If one of the number is 10then the other no is?

Please, anyone, answer this.
(2)

Krishna said:   7 years ago
4ab=(a+b)^2-(a-b)^2.
Thus (a+b) ^2-4ab=(a-b)^2..
a-b=476-424=52.
52^2=2704 =>answer.
(5)

Pritam said:   8 years ago
Nice and easy method @Bindu.
(1)

Bindu said:   9 years ago
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.
(3)

Ipsita said:   10 years ago
But as we know:

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

Siva said:   1 decade ago
[(a+b)^2-4ab] = a^2+b^2+2ab-4ab.
= (a-b)^2.
= (476-424)^2.
= 52^2.
= 2704.

Arif said:   1 decade ago
[(a+b)^2-4ab]=a^2+b^2+2ab-4ab
=(a-b)^2
=(476-424)^2
=52^2
=2704
(3)

Shahid said:   1 decade ago
[(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
(1)

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