SSC CGL 2 Sep 2016 Shif 2 Paper

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Question : 58 of 100

Marks: +1, -0

If x + 5 +

1/{x+1}

= 6 , then the value of

(x+1)^3

+

1/(x+1)^3

is

2
0
–2
4

Solution:

x + 5 +

1/{x+1}

= 6
⇒ (x + 1) =

1/(x+1)

6 - 4 = 2
On cubing both sides

\{(x + 1) + 1/(x+1)\}^3

= 8
⇒

(x+1)^3 + 1/(x+1)^2

+ 3

\{(x+1)+1/(x+1)\}

= 8
⇒

(x+1)3

+

1/(x+1)^3

+ 3 × 2 = 8
⇒

(x+1)3

+

1/(x+1)^3

= 8 - 6 = 2

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