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.
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.
Vipin Kumar said:
1 decade ago
How came x = 2+3 and y = 2-3?
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?
Jay said:
1 decade ago
Who got 2 as the correct answer? That's what I had and I'm sure I am right!
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.
Kapil said:
1 decade ago
Use:
x^2+y^2 = (x+y)^2 - 2xy.
x^2+y^2 = (x+y)^2 - 2xy.
Jessi said:
1 decade ago
x = 3*2+1/3-1 = 9+1/2 = 10/2 = 5.
y = 3*2-1/3+1 = 9-1/4 = 8/4 = 2.
The use the formula x2+y2 = 5*2+2*2 = 10+4 = 14.
y = 3*2-1/3+1 = 9-1/4 = 8/4 = 2.
The use the formula x2+y2 = 5*2+2*2 = 10+4 = 14.
Abhinav said:
1 decade ago
What if we keep the value of root 3 and proceed? the answer will be 10.
Rizy said:
1 decade ago
Solve by the normal method using formula,
(a+b)2 = a2 + 2ab + b2.
(a-b)2 = a2 - 2ab + b2.
By using this formula you will get,
8 + 6 = 14.
(a+b)2 = a2 + 2ab + b2.
(a-b)2 = a2 - 2ab + b2.
By using this formula you will get,
8 + 6 = 14.
Sakthi said:
1 decade ago
Root 3 -> 1.732.
1.732+1=2.732.
1.732-1=0.732.
2.732/0.732=3.7322.
0.732/2.732=0.2679.
(3.7322)^2=13.929 & (0.2679)^2=0.0192.
Add 13.929+0.0192=13.9482 is near by 14.
So answer is 14.
Are you clear now friends.
1.732+1=2.732.
1.732-1=0.732.
2.732/0.732=3.7322.
0.732/2.732=0.2679.
(3.7322)^2=13.929 & (0.2679)^2=0.0192.
Add 13.929+0.0192=13.9482 is near by 14.
So answer is 14.
Are you clear now friends.
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