Aptitude - Square Root and Cube Root - Discussion
Discussion Forum : Square Root and Cube Root - General Questions (Q.No. 7)
7.
| If x = | 3 + 1 | and y = | 3 - 1 | , then the value of (x2 + y2) is: |
| 3 - 1 | 3 + 1 |
Answer: Option
Explanation:
| x = | (3 + 1) | x | (3 + 1) | = | (3 + 1)2 | = | 3 + 1 + 23 | = 2 + 3. |
| (3 - 1) | (3 + 1) | (3 - 1) | 2 |
| y = | (3 - 1) | x | (3 - 1) | = | (3 - 1)2 | = | 3 + 1 - 23 | = 2 - 3. |
| (3 + 1) | (3 - 1) | (3 - 1) | 2 |
x2 + y2 = (2 + 3)2 + (2 - 3)2
= 2(4 + 3)
= 14
Discussion:
45 comments Page 2 of 5.
Chotu said:
1 decade ago
(a+b)2+(a-b)2 = 2(a2+b2).
Here a = 2 =>a2 = 4; b = 3^(1/2) =>b2 = 3.
=>2(4+3).
=>2(7).
=>14.
I think this is the correct one because this is the model of rationalization. If this is not the correct answer please explain.
How would you get the answer as 2?
Here a = 2 =>a2 = 4; b = 3^(1/2) =>b2 = 3.
=>2(4+3).
=>2(7).
=>14.
I think this is the correct one because this is the model of rationalization. If this is not the correct answer please explain.
How would you get the answer as 2?
Gopi said:
1 decade ago
The answer is to its formula (x+y)^2=x^2+y^2+2xy.
Abhirup said:
1 decade ago
The answer to this question is correct. They have just step-jumped.
Animesh said:
10 years ago
Use "(x^2+y^2) = (x+y)^2-2xy".
Here xy = 1;
Here just put the values of x and y and you can get the answer which is 14.
Here xy = 1;
Here just put the values of x and y and you can get the answer which is 14.
Bhavesh Kirange said:
10 years ago
@Jayshree.
3+1 = 4 so it becomes, 4+2√3/2.
Here take 2 common and it comes (2(2+√3))/2 = 2+√3.
3+1 = 4 so it becomes, 4+2√3/2.
Here take 2 common and it comes (2(2+√3))/2 = 2+√3.
Skrn said:
10 years ago
The question I got didn't have a root 3 value. Thanks.
KARTHI said:
9 years ago
How to solve this problem logically?
Deepak Gehlot said:
9 years ago
This is wrong solution.
Pranay Patil said:
9 years ago
Can anyone explain me why can't we solve x and y individually to get x^2 = 4 and y^2 = 1/4? So to get x^2 +y^2 = 17/4.
Shudipta Baruah said:
9 years ago
This is correct: 14
x = (3 + 1) x (3 + 1) = (3 + 1)2
= 3 + 1 + 23 = 2 + 3.
(3 - 1) (3 + 1) (3 - 1) 2.
y = (3 - 1) x (3 - 1) = (3 - 1)2 = 3 + 1 - 23 = 2 - 3.
(3 + 1) (3 - 1) (3 - 1) 2,
x2 + y2 = (2 + 3)2 + (2 - 3)2,
= 2(4 + 3),
= 14.
x = (3 + 1) x (3 + 1) = (3 + 1)2
= 3 + 1 + 23 = 2 + 3.
(3 - 1) (3 + 1) (3 - 1) 2.
y = (3 - 1) x (3 - 1) = (3 - 1)2 = 3 + 1 - 23 = 2 - 3.
(3 + 1) (3 - 1) (3 - 1) 2,
x2 + y2 = (2 + 3)2 + (2 - 3)2,
= 2(4 + 3),
= 14.
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