### Discussion :: Surds and Indices - General Questions (Q.No.15)

Ravi said: (Dec 26, 2010) | |

How the value of the (3-2 2)(3+2 2)=1? Here "2 2" means what ? |

Aparna said: (Jan 28, 2011) | |

@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 |

Shahid said: (May 20, 2011) | |

Convert the expression x into (a+b)^2 form with a=squareroot(2) and b=1 and then after that try it |

Preethi said: (Sep 23, 2011) | |

Can anyone explain this sum clearly? please. |

Hari said: (Oct 16, 2011) | |

There is no power of 2 at all. How would you get the answer ? |

Neenu said: (Dec 8, 2011) | |

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 |

Saroj said: (Jan 18, 2012) | |

Please explain the logic behind step-3. |

Anuradha said: (Feb 27, 2012) | |

Its same as (a-b)^2 formula. |

Sagar Sharma said: (Mar 6, 2012) | |

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. |

Sagar Jain said: (Apr 9, 2012) | |

What if we have to find out x^4 +x^ (-4). |

Varun said: (Apr 10, 2012) | |

Question is to find (x^1/2 - 1/x^1/2) Then there is square in the explanations first line. |

Vicky said: (Apr 10, 2012) | |

Question is to find (x^1/2 - 1/x^1/2). Then why there is square in the explanations first line. Why? |

Hima said: (Aug 8, 2012) | |

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. |

Swetha said: (Aug 31, 2013) | |

Can anyone please explain whole sum clearly how -2 came in the 2nd step of the sum? |

Gaurav Bhardwaj said: (Sep 3, 2013) | |

@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. |

Joe said: (Oct 4, 2013) | |

In first step, where did minus 2 come from ? |

Sefah said: (Mar 16, 2014) | |

How do we get the square in the 1st step because it wasn't part of the question? |

Gayathri said: (Apr 19, 2014) | |

Here given 'x' value only not root 'x'. So answer is 2(1+root2). |

Nicky said: (Sep 27, 2015) | |

Why we subtract -2 in 1st step? |

Srinivas said: (Feb 16, 2016) | |

4th step is the problem. Where did the denominator go. No proper explanation. |

Ahmed said: (Mar 2, 2016) | |

Actual answer is 4, but why should be 2. |

Suma said: (Mar 11, 2016) | |

Answer is 4 how do you get 2? |

Vijay said: (Jul 20, 2016) | |

Please explain how they take ^2over it? |

Priyanka said: (Jul 30, 2016) | |

Why -2 is wriiten at the end ? From where it came ? |

Rohit said: (Aug 3, 2016) | |

Answer is 4 how do you get 2? |

Raja Raviteja said: (Sep 2, 2016) | |

^2 = 1.414. 3 + 2^2 = 5.828. Where ^x = ^5.818 = 2.414. So, ^x - 1/^x = 2.414 - (1/2.414) = 2 =>answer. |

Priyanka said: (Oct 10, 2016) | |

Not getting this, can anyone explain clearly? |

Harshini said: (Dec 20, 2016) | |

In the 4th step, if you see the denominator: (a+b) (a-b) = (a^2-b^2) (using the formula). It becomes 3^2 -(2 root 2)^2. Which is 9 - (4 * 2), => 9 - 8 = 1. |

Saurav Kumar said: (Feb 10, 2017) | |

If x+1/x =1 then (x+1)^3 + 1/(x+1)^3 = ? Please solve it. |

Valens said: (Feb 15, 2017) | |

How 4 = 2 at last? |

Felix said: (Mar 13, 2017) | |

How did you obtain 1/x +x -2? |

Akashdeep Singh said: (May 20, 2017) | |

In the last stage where we find the value of [(underoot)x - 1/(underoot)x]^2 = 4. So if you remove the square then it will become (underoot)4 i.e. 2. (underoot)x - 1/(underoot)x = (underoot)4. (underoot)x - 1/(underoot)x = 2. |

Bishal Dey said: (Jul 25, 2017) | |

= 3+2√2 + 1/3+2√2 -2, = 3+2√2 + 3 - 2√2 -2, =6-2. =4. =√4=2. |

Harigovind C B said: (Sep 11, 2017) | |

if a÷b=4÷5 and b÷c=15÷16 , then (c^2-a^2)÷c^2+a^2 is equal to? Can anyone solve this? |

Mahima said: (Sep 23, 2017) | |

4th step how to solve the denominator (3+2√2)(3-2√2)? Please explain. |

Bfc said: (Jun 13, 2018) | |

How to solve 4th step the denominator (3+2√2) (3-2√2)? Please explain. |

Milind said: (Jan 23, 2019) | |

(√x-1/√) -2 = (x + 1/x) - 2. Can you tell me where this -2 comes from? |

Mohan said: (May 26, 2019) | |

@Joe. In the first step, it is in the form of (a-b) ^2 formula. |

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