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 5 of 5.
Anuradha said:
1 decade ago
Its same as (a-b)^2 formula.
Saroj said:
1 decade ago
Please explain the logic behind step-3.
Neenu said:
1 decade ago
x= 3+ 2(root)2
=> 2+1+2(root)2.(root)1
{which is} [(root)2+1)^2
hence, (root)x=(root)2+1
1/(root)x=1/(root)2+1 => (root)2-1
So when we add them [x+1/(root)x] = (root)2+1-[(root)2-1]=>(root)2+1-(root)+1=>2
=> 2+1+2(root)2.(root)1
{which is} [(root)2+1)^2
hence, (root)x=(root)2+1
1/(root)x=1/(root)2+1 => (root)2-1
So when we add them [x+1/(root)x] = (root)2+1-[(root)2-1]=>(root)2+1-(root)+1=>2
Hari said:
1 decade ago
There is no power of 2 at all. How would you get the answer ?
(1)
Preethi said:
1 decade ago
Can anyone explain this sum clearly? please.
Shahid said:
1 decade ago
Convert the expression x into (a+b)^2 form
with a=squareroot(2) and b=1
and then after that try it
with a=squareroot(2) and b=1
and then after that try it
Aparna said:
1 decade ago
@ravi,
Your prblm is how the denominator part came 1
see
the denominator is
(3-2 2)(3+2 2)
use the formula
(a+b)(a-b)=a2(square)-b2(square)
hence
3(square)-(2(square)*2)
here suqreroot of one 2 gets removed
we get
9-8=1
Your prblm is how the denominator part came 1
see
the denominator is
(3-2 2)(3+2 2)
use the formula
(a+b)(a-b)=a2(square)-b2(square)
hence
3(square)-(2(square)*2)
here suqreroot of one 2 gets removed
we get
9-8=1
Ravi said:
1 decade ago
How the value of the (3-2 2)(3+2 2)=1?
Here "2 2" means what ?
Here "2 2" means what ?
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