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 5 of 5.
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.
Kapil said:
1 decade ago
Use:
x^2+y^2 = (x+y)^2 - 2xy.
x^2+y^2 = (x+y)^2 - 2xy.
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!
Nithin said:
1 decade ago
(a+b)2 + (a-b)2 = 2(a2 + b2)
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers