Tuesday, December 15, 2015

Given (x+1/x) then find value of (x2+1/x2) (x3+1/x3) (x4+1/x4) …..

Quantitative Aptitude For Competitive Examinations (English) 7th Edition
Given (x+1/x) then find value of (x2+1/x2) (x3+1/x3) (x4+1/x4) …..

Let’s say (x+1/x) =4
Then Find value of (x2+1/x2)
(x2+1/x2)  can be written as (x+1/x)2 -2 
(x2+1/x2)= 4*4 -2 = 14

Let’s say of if you want to find out  (x3+1/x3)
 (x3+1/x3) can be written as ((x2+1/x2)  * (x+1/x) ) - (x+1/x)
(x3+1/x3) = 14* 4 – 4 = 52

Let’s say of if you want to find out  (x4+1/x4)
(x4+1/x4)  can be written as (x2+1/x2)2 -2
(x4+1/x4)  =  14 * 14 -2 = 194

Let’s say of if you want to find out  (x5+1/x5)
(x5+1/x5) can be written as ((x3+1/x3) (x2+1/x2))   - (x+1/x)
(x5+1/x5) = 52 * 14 – 4 = 724

Let’s say of if you want to find out  (x6+1/x6)
(x6+1/x6) can be written as  (x3+1/x3)2-2
(x6+1/x6) =  52 * 52 -2 = 2702

Similarly you can find out higher power values



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