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 3 of 5.
Rajnish Jais said:
1 decade ago
Since (x+y)^2-2xy = x^2+y^2.
x+y = 4, 2xy = 1.
Therefore, x^2+y^2 = 14.
x+y = 4, 2xy = 1.
Therefore, x^2+y^2 = 14.
Jay said:
1 decade ago
Who got 2 as the correct answer? That's what I had and I'm sure I am right!
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?
Vipin Kumar said:
1 decade ago
How came x = 2+3 and y = 2-3?
Vikas said:
1 decade ago
Could understand how {(3+2)/(3-2) }*{ (3+2)/(3+2)/(3+2)} = (3+2)^2/ (3-2), isn't it should be (3+2)^2/(3^2-1^2)? Please inform me asap.
Gopi said:
1 decade ago
The answer is to its formula (x+y)^2=x^2+y^2+2xy.
Abhirup said:
10 years 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.
Jayshree said:
10 years ago
Hello, I just didn't understand how is 3+1+2√3/2 = 2+√3.
Please explain.
Please explain.
(1)
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.
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