Aptitude - Surds and Indices - Discussion
Discussion Forum : Surds and Indices - General Questions (Q.No. 15)
15.
| If x = 3 + 22, then the value of |  |
x | - | 1 |  |
is: |
| x |
Answer: Option
Explanation:
|
x | - | 1 | |
2 | = x + | 1 | - 2 |
| x | x |
| = (3 + 22) + | 1 | - 2 |
| (3 + 22) |
| = (3 + 22) + | 1 | x | (3 - 22) | - 2 |
| (3 + 22) | (3 - 22) |
= (3 + 22) + (3 - 22) - 2
= 4.
 |
|
x | - | 1 | |
= 2. |
| x |
Discussion:
48 comments Page 4 of 5.
Gayathri said:
1 decade ago
Here given 'x' value only not root 'x'. So answer is 2(1+root2).
Sefah said:
1 decade ago
How do we get the square in the 1st step because it wasn't part of the question?
Joe said:
1 decade ago
In first step, where did minus 2 come from ?
GAURAV BHARDWAJ said:
1 decade ago
@Swetha.
If you will square that term using formulae (a-b)^2 = a^2+b^2-2ab, then you will automatically come to know how -2 came in second step.
If you will square that term using formulae (a-b)^2 = a^2+b^2-2ab, then you will automatically come to know how -2 came in second step.
Swetha said:
1 decade ago
Can anyone please explain whole sum clearly how -2 came in the 2nd step of the sum?
Hima said:
1 decade ago
3+2(root)2 can be written as 1+2(1)(root2)+ (root2)^2 which is equal to (1+root2)^2 [a^2+b^2+2ab=(a+b)^2].
So
Now x=(1+root2)^2 now put this value in the question.
So
Now x=(1+root2)^2 now put this value in the question.
Vicky said:
1 decade ago
Question is to find (x^1/2 - 1/x^1/2).
Then why there is square in the explanations first line.
Why?
Then why there is square in the explanations first line.
Why?
Varun said:
1 decade ago
Question is to find (x^1/2 - 1/x^1/2)
Then there is square in the explanations first line.
Then there is square in the explanations first line.
Sagar jain said:
1 decade ago
What if we have to find out x^4 +x^ (-4).
Sagar sharma said:
1 decade ago
The answer should have been 1. As we put the value of x in given expression and rationalize 1/x, we get 1 as the answer.
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